The short answer
Usually, after a check. Might hold something you care about. Look inside before removing it.
What is it?
Each subfolder, named with a long UUID, is one simulated iPhone, iPad, Apple Watch, Apple TV or Vision Pro: its settings plus every app you installed on it and that app’s data. Devices built for runtimes you no longer have stay here as “unavailable” simulators. The total ranges from a few hundred megabytes to tens of gigabytes.
Each simulated device with its apps and data. Unused ones can be deleted and recreated in Xcode.
What happens if you delete it?
Xcode can create a new device at any time (Window › Devices and Simulators, or it creates defaults for new runtimes), but a deleted device comes back empty. Apps installed on it, their data, files and simulator settings are lost.
How to remove it properly
Use Xcode’s Window › Devices and Simulators › Simulators, right-click a device › Delete, or run xcrun simctl delete <UUID> in Terminal; xcrun simctl delete unavailable removes every device whose runtime is no longer installed. These commands delete permanently, so quit Simulator first and keep anything you need from the devices.
Use the tool’s official command: xcrun simctl delete <device UDID>
Before you delete it
Keep simulators that hold test data, signed-in accounts or app states you rely on for manual testing.
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 delete <device UDID>) instead of deleting files — and tells you that this step can’t be undone.
Frequently asked questions
Is it safe to delete iOS simulators in CoreSimulator/Devices?
Usually, after a check. Might hold something you care about. Look inside before removing it. Xcode can create a new device at any time (Window › Devices and Simulators, or it creates defaults for new runtimes), but a deleted device comes back empty. Apps installed on it, their data, files and simulator settings are lost.
Will iOS simulators come back after I delete it?
Yes. Xcode can create a new device at any time (Window › Devices and Simulators, or it creates defaults for new runtimes), but a deleted device comes back empty. Apps installed on it, their data, files and simulator settings are lost.
How do I remove iOS simulators properly?
Use Xcode’s Window › Devices and Simulators › Simulators, right-click a device › Delete, or run xcrun simctl delete <UUID> in Terminal; xcrun simctl delete unavailable removes every device whose runtime is no longer installed. These commands delete permanently, so quit Simulator first and keep anything you need from the devices.