Finding the password for an old Apple ID

Hi folks,

I am trying to delete an old Apple ID from a new iPhone and it keeps asking for a password. I don't know the password and the email address is no longer active. My laptop is registered to my new Apple ID as is my old iPhone, but in the transition to the new phone the setting preferences seem to have diverted to the old email address as the Apple ID. Does anyone know a way around this?

Thanks,

Claire