Solved: Re: How can I make make all clips in multitrack th... - Adobe Support Community - 9789107
Right click on a keyframe, "Select all keyframes," Right click again,
"Delete selected keyframes." Easy as that. You may have to drag the clip
volume envelope to "0" if it isn't there already but you can get all of
your clips back to zero this way. I was very happy to find this
solution.