There are different products that you can get in the drugstore to put on the wart to help it go away faster. Most of these products are fairly irritating as they all contain some sort of an acid. You must be careful to put the medication only on the wart and not on the surrounding skin. More significant warts (or large numbers of warts) can be treated in the doctor's office with liquid nitrogen or other treatments. In general, I would say that if the wart is fairly small and is not affecting her at all, I would leave it alone and wait for it to go away on its own.
Warts in Children
Pediatrics Expert Advice from Shari Nethersole, M.D.