remove apple id from old iphone

If you have access to the phone, have you checked the various Settings tabs in the Settings app where you normally sign in to see if the ID shows there?

See if you can recover the ID/password. Use every email address you can think of.

Apple ID - How to find your Apple    An iCloud e-mail address is an Apple ID.

Apple ID - Find              

For the Apple ID password, enter the Apple (iCloud) ID and click Forgot Password. See if you can get an email option if necessary.

Apple ID - Manage            

Apple ID – Forgot Password