What do you do when the activation lock is using your old email and password and you forgot it
Start here:
https://support.apple.com/en-us/HT204306
If you have forgotten your AppleID username or password, try this - where you can recover your AppleID and/or associated password:
https://iforgot.apple.com/password/verify/appleid
One other thing...
If you don’t have access to either the original email account - or have failed to configure a “recovery” email address, then it going to get difficult.
If all else fails, you could contact Apple Support for assistance - if you are lucky, they may be able to help work through any other available options. You’ll find a link to Contact Support using the link at top-right of this page.
Activation Lock
