Just a damp paper towel will be best. You may have to do it several times until she is clean. Have you changed her food lately? Sometimes certain foods can give rabbits runny poop, and that can get on their bottoms.

It is possible to give a bunny a bath, we did a few times with Miss Hoppy, but only if it is a bunny who is going to stay inside until he or she is dry. Rabbits can get sick if they stay damp.