My 14 wants her last name changed to her biological fathers last name. She has my maiden last name can we do this

If everyone agrees you go to Family Court and petition for the change, no problem.

If the bio father and you agree, yes it is fairly easy. You go to courthouse, get a name change form, ( most states for this in a form) everyone signs it, files it, they may have a hearing or it may just be signed by the judge in chambers latter.