How to reset iPhone simulator

For iOS 11 and newer, you need to go the top system menu and select:

"Hardware" > "Erase All Contents and Settings..."

For iOS 14 and newer:

Device > Erase All Contents and Settings...

For iOS 11 and newer:

Hardware > Erase All Contents and Settings...

For previous versions:

Simulator > Reset Content and Settings...

(In earlier versions of the simulator the top menu entry label was "iOS Simulator"