Deverb can be done.

Deverb. I am certain that I did it by loading a negative room size into a very old version of GVerb. Don’t have or recall the version. It took echo out of a back of the room recording and gave the performer more presence. Anyone know how I can get to old versions of GVerb to prove that the functionality (although probably unintended) existed?

I’m sure you’re mistaken. Old LADSPA versions (2001) for Linux are available from here