If Sbcglobal email not working and you wish to unmerge the account, then first contact the support to settle down this issue. Because until Sbcglobal not working, then you are not able to perform any activities there. And, to unmerge the account, you need to navigate myAT&T and then type member id and password to do it. https://www.7qasearch.net/blog/fix-my-sbcglobal-email/