Thanks Tony, being locked out from removing the app scares the hell out of me. I followed your tip, but now I have 2 remnants folders and apps I can't delete, but zero bytes, so no problem. However, after restarting I still have 4 (or maybe 5) Karabiner processes running: Karabiner-DriverKit-VirtualHIDDeviceClient
karabiner_session_monitor and maybe kdc
Who knows what they're up to?