I removed the emulator and reinstalled it and got the same error.
Emulator: emulator: ERROR: Running multiple emulators with the same AVD is an experimental
This means that your AVD manager thinks that your emulator is running. It thinks that because it sees lockfiles in your avd directory. If your emulator is not running they you can (should) safely delete the lockfiles here :
$ rm $HOME/.android/avd/.avd/*.lock