I would like to know if Muslim girls are allowed to shave their legs.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

There is no evidence in the Sharee'ah that prohibits or commands shaving/removing the hair of a woman's/man's leg. Such a matter comes under the ruling that applies to the matters about which the Lawmaker (i.e. Allah) has kept silent. Thus, a person has the choice either to do or not to do.

Allah knows best.