Um ... I don't see that you're altering any contents.
If you were to Export it at that point, wouldn't it export those tracks as muted?
I recently did a recording at a music festival - I had 3 cameras, each with it's own audio recording so I could synchronise everything together, plus a 6-channel field recorder with its own good microphones which I intended to use for the audio in in the final output. So that's a lot of audio tracks and I spent a lot of time tweaking and adjusting my audio and I did end up mixing in some content picked up by one of the cameras because it had some interesting crowd noises I wanted. So I'd be reluctant to take any chances undoing that work by messing around with the individual audio tracks.
Will Ann's suggestion of using the Master (-100) return everything to how I had it when I put it back to 0.0?
On PC, just access the Volume Mixer (lower right of Windows screen = little speaker thingy) and MUTE Premiere, done! Not changing ANYTHING in Premiere that might bite you later.

Thanks
Jeff Pulera
Safe Harbor Computers