Thank you for your help!!

Same thing happened to me except I used to have sbcglobal.net account.

The problem was I could not log in to att.com account as usafa92 suggested. I tried to contact Alex and another person gave me this phone number 877-312-5550.

After only (?) one transfer, tech guy helped me to log in att.com account (he made arrangement to do *****@sbcglobal.net as user ID and gave me temporal password). He told me he can't help to unmerge, but after being able to log in att.com account and follow usafe92's instruction, finally say goodbye to att (sbcglobal) net account!!

Hope it will help some others!!