Change rescue account

There are instructions on this page for editing/removing it :

1. Navigate to appleid.apple.com using your web browser.
2. Click "Manage your account"
3. When prompted, sign in using your Apple ID and password.
4. Click Password & Security
5. You'll be asked to answer 2 of your 3 security questions before you can make any modifications. If you are unable to remember your answers, you can choose to send an email to your rescue email to reset your security questions.
6. After you've validated your identity by correctly answering your security questions, click Editto the right of your rescue email address.
7. Once you've finished editing your rescue email address, click the Savebutton directly below the email field.

You should then be able to use that as your main address