how can I disable the video and only play the audio?
Simple, depends on what you want.
1. Not have the video at all on the timeline. Get the video and audio on separate tracks (shortcut Ctrl+H), ungroup using the ungroup button (Shift+G), delete the video part from timeline. If you always want video and audio on separate tracks like me, then go to Program Settings, Video/Audio tab, under Timeline, uncheck Video/Audio on one track.
2. Keep the video on a track but not see just that video clip and still see others on that track. Get the video and audio on separate tracks. Lower the opacity handle, the one in the middle of the image/video, to the bottom.
3. Keep the video(s) on a track but no longer see any videos on that track. Get the video and audio on separate tracks. Turn on the Mute button in the track header of the video track.