The short answer
Usually, after a check. Might hold something you care about. Look inside before removing it.
What is it?
Recent Xcode versions download iOS simulator runtimes as system-managed assets, stored in /System/Library/AssetsV2/com_apple_MobileAsset_iOSSimulatorRuntime, and mount them for the simulator. Each .asset folder is one runtime, typically 7 to 10 GB. This location is protected by System Integrity Protection.
Where recent Xcode versions actually store iOS simulator runtimes, 7-10 GB each. Removed through Xcode's runtime manager; can be downloaded again.
What happens if you delete it?
A removed runtime can be downloaded again from Xcode › Settings › Components. Simulators built on it are unavailable until you do.
How to remove it properly
Use Xcode › Settings › Components, or run xcrun simctl runtime list and xcrun simctl runtime delete <identifier> in Terminal (permanent). Finder cannot move these folders to the Trash, even with an administrator password, because the system protects them.
Use the tool’s official command: xcrun simctl runtime delete <runtime>
Before you delete it
If a runtime still appears here but no longer shows up in xcrun simctl runtime list, it is orphaned; restarting the Mac sometimes lets the system clean it up, otherwise Apple’s own tools are the only supported way to remove it.
How MoreRoom helps
MoreRoom recognises this item and labels it “Review first”: it shows what’s inside, its size and last use, so you can decide. Nothing is removed without your say, and everything goes to the Trash first, with Undo.
When the tool is installed, MoreRoom runs its official command for you (xcrun simctl runtime delete <runtime>) instead of deleting files — and tells you that this step can’t be undone.
Frequently asked questions
Can I delete simulator runtimes in /System/Library/AssetsV2?
Usually, after a check. Might hold something you care about. Look inside before removing it. A removed runtime can be downloaded again from Xcode › Settings › Components. Simulators built on it are unavailable until you do.
Will iOS simulator runtimes (downloaded images) come back after I delete it?
Yes. A removed runtime can be downloaded again from Xcode › Settings › Components. Simulators built on it are unavailable until you do.
How do I remove iOS simulator runtimes (downloaded images) properly?
Use Xcode › Settings › Components, or run xcrun simctl runtime list and xcrun simctl runtime delete <identifier> in Terminal (permanent). Finder cannot move these folders to the Trash, even with an administrator password, because the system protects them.