I use therma-loc all the time, I like it alot. No I do not think there is a solvent, I called GRS and asked same that question years ago. I was accustomed to using shellac and dissolving it, but no-can-do with this. The little left over bits will stick well to a softened piece and pull right out or you can pick and flick them off with a tweezers or pick once they are hard. That's what I'd suggest.
You have to adjust your practices a bit and fasten your piece without filling the holes and hard to reach tight spots with it.
I have a shop microwave that I never use for food and I always soften it by boiling water in a beaker, removing it and then dropping a blob in until soft. You can microwave the beaker of water with the blob submerged if you're in a hurry. I never overheat the thermo-plastic this way.