First of all, you must know that you are not allowed to** access my att Yahoo email account** to unmerge account on your mobile device. So, you have to use your laptop or desktop to do it. For it, you have to access general tab to snap on the Settings tab. Next, you have to snap on the account and then on the Import. Now, you can delete or edit accounts accordingly. https://www.numbersupportcustomerservice.com/blog/access-my-att-email-account/