I accidentally removed the Library/CoreSimulator/Devices directory. I no longer have any IOS Simulator devices.
I un-installed Xcode and re-installed, but it did not restore the IOS simulator devices.
Is there another way to restore the simulator devices (without restoring from a backup)?
Just go to Window->Devices menu in Xcode then add the wanted simulators by taping the "+" button in the lower left corner of the window.
It sounds like you just didn't kill the service. If you want to return to a purely vanilla state, you can do:
1) Quit Xcode, Simulator, Instruments, etc.
2) Run in Terminal: 'sudo killall -9 com.apple.CoreSimulator.CoreSimulatorService'
3) Run in Terminal: 'rm -rf ~/Library/*/CoreSimulator'