How do I reset the Simulator in Xcode 9
Xcode 9.4
You need to click on Simulator first. Hardware > Erase All Content and Settings. This will reset the simulator. Wait for a minute for the Simulator to rebuild.
Xcode 11.4
The simulator app no longer has the Hardware
menu. It is now the Device
menu.
Device > Erase All Content and Settings
I found it. It is now under "Hardware -> Erase All Content and Settings"
Edit: In Xcode 11 it is now under "Device -> Erase All Content and Settings"