Is it safe to delete Simulator devices?
Your data Only if you're sure.
Simulators and the apps and data installed in them. Removing a device resets it.
Simulator or Xcode uses it while open, so ClearMac skips it until you quit Simulator or Xcode.
Where it is
~/Library/Developer/CoreSimulator/Devices
What “Your data” means
This may be the only copy of something you care about. ClearMac never pre-selects it, and moves it to the Trash only if you choose it yourself.
How ClearMac handles it
ClearMac lists it with this label but never pre-selects it. If you choose it, it goes to the Trash, so you can put it back until you empty the Trash.
This page is generated from the same rule ClearMac uses on your Mac (simulator.devices), so the app and this page always say the same thing.