I've got a really old account, too - but it is active.
As yours is not active, wait here and a member of the Forum Team will contact you. They will send you a private forum message to take your personal details and check security if necessary. Then they will pass the case to the email team to permanently delete the orphaned email address from the system. If you do still have access, now is the time to save any contacts or emails that are important to you.
Be patient, they work through the forum in date order so it could be minutes or days until they reach this post.