If the grips are really stuck to the frame you can try backing the screw out as far a possible then give it a push to pop the other side of the grip off.

Doing it that way helps keep the grip straight while coming off as not to pop off or damage any wood. Some even say to tap the screw with the back of a screwdriver but usually just pushing will work.

Saw Peak beat me to it. I type very slow. LOL