Can't remember Apple ID password
i have my mother in law iphone and trying to help her..... but there is a problem we are trying to reset the whole phone and she cant remember the apple id password she has had so many i phones and cant remember the password to this one. i need help just putting or trying to reset the whole phone to get everything cleared off. HELP!!!!!!!!!! please and thank you
[Re-Titled by Moderator]
iPhone 5