very sorry to hear about your losing a band member.
in reaper and other daw packages you could try a noise gate
carefully applied together with mouse editing.
in reaper is also a feature called "REAFIR" that might be usefull carefully applied.
another idea might be there are lots of seasoned people on these forums with audio engineering backgrounds...
thus you could post the audio trak somewhere , and see
if people on these forums could clean it up for you.
there are lots of techniques. sometimes requiring lots of subtle work on a trak.

best
oldmuso


my songs....mixed for good earbuds...(fyi..my vocs on all songs..)
https://soundcloud.com/alfsongs
(90 songs created useing bb/rb)
(lots of tips of mine in pg tips forum.)