If this was Greatdy system audio (a Soundflower alternative that does not work for most people), download the GreatdyAudioDevice New app from https://drive.google.com/file/d/0B7u-ChIr3ATUYm9xNHdoTjlKME1odE1QM1lrWDN3MlV6ZnRF/view, run the app and choose the option to uninstall.
If you want an alternative app, you can try Sound Siphon: http://staticz.com/soundsiphon/. The free version can record all sounds playing on the computer, but can’t choose which apps to record from. You only need to set the output device in System Sound Preferences to Sound Siphon and the recording device in Audacity to Sound Siphon.
Turn Audacity’s Software Playthrough off, because you have the ability to hear audio when Sound Siphon is the system output device.
The recording volume is fixed irrespective of output level, so if you want to turn down the sound while recording, turn down either the Sound Siphon output slider in System Preferences or the Playback Volume slider in Audacity.
Gale