How do I remove all these extra simulators from my Xcode menu?
You don't need to delete the Simulators you don't want to see on the run destinations drop-down menu. On Xcode 9 you can just hide the ones that you don't need.
Go to Window > Devices and Simulators (ShiftCmd2)
Pick the Simulator from the left and untick 'Show as run destination' as seen below:
There is a nice shell script that deletes all simulators and creates a list of new ones for you on GitHub without the need of Fastlane (even though Fastlane is worth to have anyway):
https://github.com/jerolimov/reset_simulators
XCode > Window > Devices :
Then use the delete key or click the gear icon to remove simulators.
You can remove devices easily now in XCode 9, but use the Simulator toolbar. With a Simulator running, go to the top bar and go to Hardware -> Device -> Manage Devices then select Simulators. You are presented with the option [Devices | Simulators] So select simulators. Then work your way down the list, and untick the Simulators, and OS versions you don't want. Too easy. When you look in XCode for a Simulator to use, the list will now be much shorter. Removing unwanted Simulators
If you want to do this quickly I'd recommend fastlane tools you can reset simulators with one line
fastlane snapshot reset_simulators
install fastlane tools
sudo gem install fastlane
Make sure, you have the latest version of the Xcode command line tools installed:
xcode-select --install
(https://docs.fastlane.tools/actions/capture_ios_screenshots#completely-reset-all-simulators)
And the command is
fastlane snapshot reset_simulators