Removing playback channels from mixer?

It's exactly as it sounds. I'm trying to listen to playback with different channels soloed, but because I'm making a jazz chart with chords over each part for soloing, the mixer is cluttered with 12 or so playback channels, and I really only need one for what I'm doing.

Is there a way for me to just remove these other channels? I'm not seeing an option anywhere for it.