diff --git a/README.md b/README.md
index 55fdbec8..ad42d05d 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,9 @@ XcodesApp is now part of the `XcodesOrg` - [read more here](nextstep.md)
 ## Platforms/Runtimes
 
 - Xcodes supports downloading the Apple runtimes via the app. Simply click on the Platform, and Xcodes will install automatically for you.
+- Platforms are listed in the order iOS, watchOS, visionOS, tvOS, with the newest version first.
+- Uninstall an installed platform with the **Uninstall** button next to it in the Xcode's Platforms list.
+- When uninstalling an Xcode, choose **Uninstall with Platforms** to also remove the simulator platforms that only that Xcode uses. Platforms that another installed Xcode still uses are never offered for removal.
 
 **Note: iOS 18+, tvOS 18+, watchOS 11+, visionOS 2+ requires that Xcode 16.1 Beta 3+ be installed and active.** 
 
diff --git a/Xcodes/Backend/AppState+Runtimes.swift b/Xcodes/Backend/AppState+Runtimes.swift
index 78cf486e..4fc1ce35 100644
--- a/Xcodes/Backend/AppState+Runtimes.swift
+++ b/Xcodes/Backend/AppState+Runtimes.swift
@@ -285,7 +285,8 @@ extension AppState {
         }
     }
 
-    func confirmDeleteRuntime(runtime: DownloadableRuntime) {
+    /// - Parameter presentErrorInSettings: Show failures in the Settings window (Platforms list) instead of the main window.
+    func confirmDeleteRuntime(runtime: DownloadableRuntime, presentErrorInSettings: Bool = true) {
         deleteRuntimeTask?.cancel()
         let taskID = UUID()
         deleteRuntimeTaskID = taskID
@@ -303,11 +304,51 @@ extension AppState {
             } catch is CancellationError {
             } catch {
                 guard self.deleteRuntimeTaskID == taskID else { return }
-                self.presentedPreferenceAlert = .generic(
-                    title: "Error",
-                    message: self.runtimeDeletionErrorMessage(error)
-                )
+                self.presentRuntimeDeletionError(error, runtime: runtime, inSettings: presentErrorInSettings)
+            }
+        }
+    }
+
+    /// Shows why a platform couldn't be removed. When it failed because no Xcode is active,
+    /// offers to make the newest installed release active and try again.
+    func presentRuntimeDeletionError(_ error: Error, runtime: DownloadableRuntime, inSettings: Bool) {
+        let message = runtimeDeletionErrorMessage(error)
+        if Self.isMissingDeveloperToolError(message) {
+            if inSettings {
+                presentedPreferenceAlert = .noActiveXcode(runtime: runtime, xcode: latestInstalledReleaseXcode)
+            } else {
+                presentedAlert = .noActiveXcode(runtime: runtime, xcode: latestInstalledReleaseXcode)
             }
+        } else if inSettings {
+            presentedPreferenceAlert = .generic(title: "Error", message: message)
+        } else {
+            presentedAlert = .generic(title: "Error", message: message)
+        }
+    }
+
+    /// `xcrun` reports this when the active developer directory is the Command Line Tools,
+    /// which don't include `simctl`.
+    static func isMissingDeveloperToolError(_ message: String) -> Bool {
+        message.contains("unable to find utility") || message.contains("requires Xcode")
+    }
+
+    /// The newest installed Xcode that isn't a beta or release candidate.
+    var latestInstalledReleaseXcode: Xcode? {
+        allXcodes
+            .filter { $0.installState.installed && $0.version.prereleaseIdentifiers.isEmpty }
+            .max { $0.version < $1.version }
+    }
+
+    /// Makes the Xcode active, then tries removing the platform again.
+    func selectXcodeAndDeleteRuntime(xcode: Xcode, runtime: DownloadableRuntime, presentErrorInSettings: Bool) {
+        select(xcode: xcode)
+        Task { @MainActor [weak self] in
+            // select(xcode:) starts selectTask right away unless it first has to ask to install the helper;
+            // in that case the user can remove the platform again once the Xcode is active.
+            guard let self, let selectTask = self.selectTask else { return }
+            await selectTask.value
+            guard let path = xcode.installedPath?.string, self.selectedXcodePath?.hasPrefix(path) == true else { return }
+            self.confirmDeleteRuntime(runtime: runtime, presentErrorInSettings: presentErrorInSettings)
         }
     }
 
@@ -319,3 +360,57 @@ extension AppState {
         return error.localizedDescription
     }
 }
+
+// MARK: - Platforms of an Xcode
+
+extension DownloadableRuntime.Platform {
+    /// The order platforms are listed in: iOS, watchOS, visionOS, tvOS.
+    var displayOrder: Int {
+        switch self {
+        case .iOS: return 0
+        case .watchOS: return 1
+        case .visionOS: return 2
+        case .tvOS: return 3
+        case .macOS: return 4
+        }
+    }
+}
+
+extension AppState {
+    /// Installed simulator runtimes that match this Xcode's SDKs and no other installed Xcode's,
+    /// so they can be offered for removal along with it.
+    func installedRuntimesUsedOnly(by xcode: Xcode) -> [DownloadableRuntime] {
+        func runtimes(matching xcode: Xcode) -> Set<String> {
+            let builds = xcode.sdks?.allBuilds ?? []
+            return Set(downloadableRuntimes
+                .filter { runtime in builds.contains { runtime.sdkBuildUpdate?.contains($0) ?? false } }
+                .map(\.identifier))
+        }
+
+        let otherInstalledXcodes = allXcodes.filter { $0.id != xcode.id && $0.installState.installed }
+        let usedElsewhere = otherInstalledXcodes.reduce(into: Set<String>()) { $0.formUnion(runtimes(matching: $1)) }
+        let candidates = runtimes(matching: xcode).subtracting(usedElsewhere)
+
+        return downloadableRuntimes
+            .filter { candidates.contains($0.identifier) && coreSimulatorInfo(runtime: $0) != nil }
+            .sorted { ($0.platform.displayOrder, $1.name) < ($1.platform.displayOrder, $0.name) }
+    }
+
+    /// Uninstalls an Xcode, then removes the given simulator runtimes.
+    func uninstall(xcode: Xcode, removingRuntimes runtimes: [DownloadableRuntime]) {
+        uninstall(xcode: xcode)
+        guard !runtimes.isEmpty else { return }
+        Task { @MainActor [weak self] in
+            // Remove the platforms once the Xcode itself is gone, so a failure there doesn't leave it half-removed
+            await self?.uninstallTask?.value
+            for runtime in runtimes {
+                do {
+                    try await self?.deleteRuntime(runtime: runtime)
+                } catch {
+                    self?.presentRuntimeDeletionError(error, runtime: runtime, inSettings: false)
+                    return
+                }
+            }
+        }
+    }
+}
diff --git a/Xcodes/Frontend/Common/XcodesAlert.swift b/Xcodes/Frontend/Common/XcodesAlert.swift
index 710668f9..5224b1de 100644
--- a/Xcodes/Frontend/Common/XcodesAlert.swift
+++ b/Xcodes/Frontend/Common/XcodesAlert.swift
@@ -1,4 +1,5 @@
 import Foundation
+import SwiftUI
 import XcodesKit
 
 enum XcodesAlert: Identifiable {
@@ -8,6 +9,8 @@ enum XcodesAlert: Identifiable {
     case generic(title: String, message: String)
     case checkMinSupportedVersion(xcode: AvailableXcode, macOS: String)
     case unauthenticated
+    case deletePlatform(runtime: DownloadableRuntime)
+    case noActiveXcode(runtime: DownloadableRuntime, xcode: Xcode?)
 
     var id: Int {
         switch self {
@@ -17,6 +20,8 @@ enum XcodesAlert: Identifiable {
         case .checkMinSupportedVersion: return 4
         case .cancelRuntimeInstall: return 5
         case .unauthenticated: return 6
+        case .deletePlatform: return 8
+        case .noActiveXcode: return 9
         }
     }
 }
@@ -26,11 +31,37 @@ enum XcodesAlert: Identifiable {
 enum XcodesPreferencesAlert: Identifiable {
     case deletePlatform(runtime: DownloadableRuntime)
     case generic(title: String, message: String)
+    case noActiveXcode(runtime: DownloadableRuntime, xcode: Xcode?)
     
     var id: Int {
         switch self {
         case .deletePlatform: return 1
         case .generic: return 2
+        case .noActiveXcode: return 3
+        }
+    }
+}
+
+extension Alert {
+    /// Removing a platform runs `simctl`, which only comes with Xcode. Offers to make the newest installed release active and retry.
+    @MainActor
+    static func noActiveXcode(appState: AppState, runtime: DownloadableRuntime, xcode: Xcode?, inSettings: Bool) -> Alert {
+        let explanation = String(format: localizeString("Alert.NoActiveXcode.Message"), runtime.name, appState.selectedXcodePath ?? "–")
+        guard let xcode else {
+            return Alert(
+                title: Text("Alert.NoActiveXcode.Title"),
+                message: Text(verbatim: explanation + "\n\n" + localizeString("Alert.NoActiveXcode.NoneInstalled")),
+                dismissButton: .default(Text("OK"))
+            )
         }
+        return Alert(
+            title: Text("Alert.NoActiveXcode.Title"),
+            message: Text(verbatim: explanation),
+            primaryButton: .default(
+                Text(String(format: localizeString("Alert.NoActiveXcode.PrimaryButton"), xcode.description)),
+                action: { appState.selectXcodeAndDeleteRuntime(xcode: xcode, runtime: runtime, presentErrorInSettings: inSettings) }
+            ),
+            secondaryButton: .cancel(Text("Cancel"))
+        )
     }
 }
diff --git a/Xcodes/Frontend/InfoPane/PlatformsView.swift b/Xcodes/Frontend/InfoPane/PlatformsView.swift
index 34af471e..5435e646 100644
--- a/Xcodes/Frontend/InfoPane/PlatformsView.swift
+++ b/Xcodes/Frontend/InfoPane/PlatformsView.swift
@@ -32,6 +32,13 @@ struct PlatformsView: View {
             guard !(runtime.architectures?.isEmpty ?? true), let displayedVariant else { return true }
             return runtime.supports(displayedVariant)
         }
+        // iOS, watchOS, visionOS, tvOS; newest version first within a platform
+        .sorted { lhs, rhs in
+            if lhs.platform.displayOrder != rhs.platform.displayOrder {
+                return lhs.platform.displayOrder < rhs.platform.displayOrder
+            }
+            return lhs.simulatorVersion.version.localizedStandardCompare(rhs.simulatorVersion.version) == .orderedDescending
+        }
         
         VStack {
             HStack {
@@ -84,20 +91,20 @@ struct PlatformsView: View {
                 }
                
                 pathIfAvailable(xcode: xcode, runtime: runtime)
-                
-                if runtime.installState == .notInstalled {
-                    // TODO: Update the downloadableRuntimes with the appropriate installState so we don't have to check path awkwardly
-                    if appState.runtimeInstallPath(xcode: xcode, runtime: runtime) != nil {
-                        EmptyView()
-                    } else {
-                        HStack {
-                            Spacer()
-                            DownloadRuntimeButton(runtime: runtime)
-                        }
+
+                // One spacer, so the action button sits next to the size column on every row
+                Spacer()
+
+                // TODO: Update the downloadableRuntimes with the appropriate installState so we don't have to check path awkwardly
+                if appState.runtimeInstallPath(xcode: xcode, runtime: runtime) != nil {
+                    Button("Uninstall", role: .destructive) {
+                        appState.presentedAlert = .deletePlatform(runtime: runtime)
                     }
+                    .help("Alert.DeletePlatform.PrimaryButton")
+                } else if runtime.installState == .notInstalled {
+                    DownloadRuntimeButton(runtime: runtime)
                 }
-					
-                Spacer()
+
                 Text(runtime.downloadFileSizeString)
                     .font(.subheadline)
 						  .frame(width: 70, alignment: .trailing)
diff --git a/Xcodes/Frontend/MainWindow.swift b/Xcodes/Frontend/MainWindow.swift
index b108f053..b4997da8 100644
--- a/Xcodes/Frontend/MainWindow.swift
+++ b/Xcodes/Frontend/MainWindow.swift
@@ -22,11 +22,26 @@ struct MainWindow: View {
         NavigationSplitViewWrapper {
             XcodeListView(selectedXcodeID: $selectedXcodeID, searchText: searchText, category: category, isInstalledOnly: isInstalledOnly, architecture: architecture)
                 .layoutPriority(1)
-                .alert(item: $appState.xcodeBeingConfirmedForUninstallation) { xcode in
-                    Alert(title: Text(String(format: localizeString("Alert.Uninstall.Title"), xcode.description)),
-                          message: Text("Alert.Uninstall.Message"),
-                          primaryButton: .destructive(Text("Uninstall"), action: { self.appState.uninstall(xcode: xcode) }),
-                          secondaryButton: .cancel(Text("Cancel")))
+                .alert(
+                    Text(String(format: localizeString("Alert.Uninstall.Title"), appState.xcodeBeingConfirmedForUninstallation?.description ?? "")),
+                    isPresented: $appState.xcodeBeingConfirmedForUninstallation.isNotNil,
+                    presenting: appState.xcodeBeingConfirmedForUninstallation
+                ) { xcode in
+                    let platforms = appState.installedRuntimesUsedOnly(by: xcode)
+                    Button("Uninstall", role: .destructive) { appState.uninstall(xcode: xcode) }
+                    if !platforms.isEmpty {
+                        Button("Alert.Uninstall.WithPlatforms", role: .destructive) {
+                            appState.uninstall(xcode: xcode, removingRuntimes: platforms)
+                        }
+                    }
+                    Button("Cancel", role: .cancel) {}
+                } message: { xcode in
+                    let platforms = appState.installedRuntimesUsedOnly(by: xcode)
+                    if platforms.isEmpty {
+                        Text("Alert.Uninstall.Message")
+                    } else {
+                        Text(verbatim: localizeString("Alert.Uninstall.Message") + "\n\n" + String(format: localizeString("Alert.Uninstall.PlatformsMessage"), platforms.map(\.visibleIdentifier).joined(separator: ", ")))
+                    }
                 }
                 .searchable(text: $searchText, placement: .sidebar)
                 .mainToolbar(
@@ -204,6 +219,17 @@ struct MainWindow: View {
                     Text("Cancel")
                 )
             )
+        case let .noActiveXcode(runtime, xcode):
+            return .noActiveXcode(appState: appState, runtime: runtime, xcode: xcode, inSettings: false)
+        case let .deletePlatform(runtime):
+            return Alert(
+                title: Text(String(format: localizeString("Alert.DeletePlatform.Title"), runtime.name)),
+                primaryButton: .destructive(
+                    Text("Alert.DeletePlatform.PrimaryButton"),
+                    action: { appState.confirmDeleteRuntime(runtime: runtime, presentErrorInSettings: false) }
+                ),
+                secondaryButton: .cancel(Text("Cancel"))
+            )
         case let .checkMinSupportedVersion(xcode, deviceVersion):
             return Alert(
                 title: Text("Alert.MinSupported.Title"),
diff --git a/Xcodes/Frontend/Preferences/PlatformsListView.swift b/Xcodes/Frontend/Preferences/PlatformsListView.swift
index d789e8a5..472eca9b 100644
--- a/Xcodes/Frontend/Preferences/PlatformsListView.swift
+++ b/Xcodes/Frontend/Preferences/PlatformsListView.swift
@@ -20,7 +20,7 @@ struct PlatformsListView: View {
         List(selection: $selectedRuntime) {
             Text("PlatformsList.Title")
                 .font(.body)
-            ForEach(runtimes.elements.sorted(\.key.order), id: \.key) { platform, runtimeList in
+            ForEach(runtimes.elements.sorted(\.key.displayOrder), id: \.key) { platform, runtimeList in
                 Section {
                     ForEach(runtimeList, id: \.self) { runtime in
                         HStack {
diff --git a/Xcodes/Resources/Localizable.xcstrings b/Xcodes/Resources/Localizable.xcstrings
index 6608a149..5803a1e7 100644
--- a/Xcodes/Resources/Localizable.xcstrings
+++ b/Xcodes/Resources/Localizable.xcstrings
@@ -2971,6 +2971,50 @@
         }
       }
     },
+    "Alert.NoActiveXcode.Message" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Removing %1$@ uses simctl, which comes with Xcode. The active developer directory is %2$@, which doesn't include it."
+          }
+        }
+      }
+    },
+    "Alert.NoActiveXcode.NoneInstalled" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Install a release of Xcode, make it active, then try again."
+          }
+        }
+      }
+    },
+    "Alert.NoActiveXcode.PrimaryButton" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Make %@ Active and Retry"
+          }
+        }
+      }
+    },
+    "Alert.NoActiveXcode.Title" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "No Xcode Is Active"
+          }
+        }
+      }
+    },
     "Alert.PostInstall.Title" : {
       "comment" : "Post install",
       "extractionState" : "manual",
@@ -4282,6 +4326,17 @@
         }
       }
     },
+    "Alert.Uninstall.PlatformsMessage" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "These simulator platforms are installed for this Xcode and not used by your other installed Xcodes: %@"
+          }
+        }
+      }
+    },
     "Alert.Uninstall.Title" : {
       "comment" : "Uninstall",
       "extractionState" : "manual",
@@ -4414,6 +4469,16 @@
         }
       }
     },
+    "Alert.Uninstall.WithPlatforms" : {
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Uninstall with Platforms"
+          }
+        }
+      }
+    },
     "Alert.Update.Error.Title" : {
       "comment" : "Update",
       "extractionState" : "manual",
diff --git a/Xcodes/XcodesApp.swift b/Xcodes/XcodesApp.swift
index 0d46447a..9d25b01f 100644
--- a/Xcodes/XcodesApp.swift
+++ b/Xcodes/XcodesApp.swift
@@ -91,6 +91,8 @@ struct XcodesApp: App {
     
     private func alert(for alertType: XcodesPreferencesAlert) -> Alert {
         switch alertType {
+        case let .noActiveXcode(runtime, xcode):
+            return .noActiveXcode(appState: appState, runtime: runtime, xcode: xcode, inSettings: true)
         case let .deletePlatform(runtime):
             return Alert(
                 title: Text(String(format: localizeString("Alert.DeletePlatform.Title"), runtime.name)),
diff --git a/XcodesTests/AppStateUpdateTests.swift b/XcodesTests/AppStateUpdateTests.swift
index 299e4f01..bed793c3 100644
--- a/XcodesTests/AppStateUpdateTests.swift
+++ b/XcodesTests/AppStateUpdateTests.swift
@@ -78,6 +78,89 @@ class AppStateUpdateTests: XCTestCase {
         XCTAssertEqual(subject.selectedXcodePath, "/Applications/Xcode-Beta.app")
     }
 
+    func test_InstalledRuntimesUsedOnlyByXcode_SkipsSharedAndNotInstalledPlatforms() throws {
+        subject.downloadableRuntimes = try [
+            platformRuntime(platform: "iphoneos", identifier: "ios-27.0", sdkBuild: "24A430", simulatorBuild: "24A434"),
+            platformRuntime(platform: "watchos", identifier: "watch-27.0", sdkBuild: "24R360", simulatorBuild: "24R362"),
+            platformRuntime(platform: "appletvos", identifier: "tv-27.0", sdkBuild: "24J360", simulatorBuild: "24J360"),
+        ]
+        subject.installedRuntimes = [
+            CoreSimulatorImage(uuid: "1", path: [:], runtimeInfo: CoreSimulatorRuntimeInfo(build: "24A434", supportedArchitectures: [.arm64])),
+            CoreSimulatorImage(uuid: "2", path: [:], runtimeInfo: CoreSimulatorRuntimeInfo(build: "24R362", supportedArchitectures: [.arm64])),
+        ]
+        let uninstalling = Xcode(
+            version: Version("27.0.0+27A266a")!,
+            installState: .installed(Path("/Applications/Xcode-27.0.0.app")!),
+            selected: false,
+            icon: nil,
+            sdks: SDKs(iOS: XcodeVersion("24A430"), watchOS: XcodeVersion("24R360"), tvOS: XcodeVersion("24J360")),
+            architectures: [.arm64]
+        )
+        // Another installed Xcode still uses the watchOS runtime
+        let other = Xcode(
+            version: Version("27.1.0-beta+27A9269")!,
+            installState: .installed(Path("/Applications/Xcode-27.1.0-Beta.app")!),
+            selected: false,
+            icon: nil,
+            sdks: SDKs(watchOS: XcodeVersion("24R360")),
+            architectures: [.arm64]
+        )
+        subject.allXcodes = [uninstalling, other]
+
+        // tvOS matches but isn't installed; watchOS is shared
+        XCTAssertEqual(subject.installedRuntimesUsedOnly(by: uninstalling).map(\.identifier), ["ios-27.0"])
+    }
+
+    func test_LatestInstalledReleaseXcode_SkipsBetasAndNotInstalled() {
+        func xcode(_ version: String, installed: Bool) -> Xcode {
+            Xcode(
+                version: Version(version)!,
+                installState: installed ? .installed(Path("/Applications/Xcode-\(version).app")!) : .notInstalled,
+                selected: false,
+                icon: nil
+            )
+        }
+        subject.allXcodes = [
+            xcode("27.2.0-beta.2+27B5028f", installed: true),
+            xcode("27.1.0+27B100", installed: false),
+            xcode("27.0.0+27A266a", installed: true),
+            xcode("26.6.0+17G1", installed: true),
+        ]
+
+        XCTAssertEqual(subject.latestInstalledReleaseXcode?.version, Version("27.0.0+27A266a"))
+    }
+
+    func test_LatestInstalledReleaseXcode_NilWithOnlyBetas() {
+        subject.allXcodes = [
+            Xcode(version: Version("27.2.0-beta.2+27B5028f")!, installState: .installed(Path("/Applications/Xcode-Beta.app")!), selected: false, icon: nil)
+        ]
+
+        XCTAssertNil(subject.latestInstalledReleaseXcode)
+    }
+
+    func test_IsMissingDeveloperToolError() {
+        XCTAssertTrue(AppState.isMissingDeveloperToolError(#"xcrun: error: unable to find utility "simctl", not a developer tool or in PATH"#))
+        XCTAssertTrue(AppState.isMissingDeveloperToolError("xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance"))
+        XCTAssertFalse(AppState.isMissingDeveloperToolError("No simulator found with ios-27.0"))
+    }
+
+    private func platformRuntime(platform: String, identifier: String, sdkBuild: String, simulatorBuild: String) throws -> DownloadableRuntime {
+        let json: [String: Any] = [
+            "sdkBuildUpdate": [sdkBuild],
+            "architectures": ["arm64"],
+            "name": identifier,
+            "platform": "com.apple.platform.\(platform)",
+            "simulatorVersion": ["version": "27.0", "buildUpdate": simulatorBuild],
+            "contentType": "cryptexDiskImage",
+            "dictionaryVersion": 2,
+            "version": "27.0.0.1",
+            "category": "simulator",
+            "identifier": identifier,
+            "fileSize": 1,
+        ]
+        return try JSONDecoder().decode(DownloadableRuntime.self, from: JSONSerialization.data(withJSONObject: json))
+    }
+
     func testDoesNotReplaceInstallState() throws {
         subject.allXcodes = [
             Xcode(version: Version("0.0.0")!, installState: .installing(.unarchiving), selected: false, icon: nil)