A BattleTag can only be updated for free once

It is not possible to move a Call of Duty account to another Battle.net account

Information on where to update your Activsion Account Email

Regaining access to a Battle.net Account when the email is not accessible.

What to do if your Activision account has been compromised.

What to do if your Steam account has been compromised.

How to pay with an alternate PayPal account

If you're seeing this message, check your email for details about the violation and a link to information on the appeals process.

Information on transferring an account between a parent or legal guardian and a child

Information on the deletion, transfer, unlinking, or moving accounts.