A lot of third-party audio/video app (Screen recording apps) will install the additional audio device in the system preference panel.
To list all third party kernel extensions in Mac OS X:
kextstat | grep -v com.apple
To uninstall the extension:
sudo kextunload -b NAME_OF_THE_EXTENSION
e.g. sudo kextunload -b com.globaldelight.driver.Boom2Device