Forgot Password, trusted phone number disconnected

How do I access "my account" page to change a /password/phone number/ when the trusted phone number to which messages are sent no longer exists?

My daughter gave her iphone6 to her daughter and tried to reset the phone for daughter to use but it will not let her since she does not remember the password and the trusted phone number that is listed is no longer in service and she never changed it on her account page.