To cancel your AT&T account you will need to call into support. But before, you should find another provider and check to see if your number is portable, meaning you can bring the phone number to another company.
The issue in GetHuman-devantae's own words
I need to cancel this membership. I’ve tried cancelling it before but I have multiple emails and I am unsure which one the account is for.
GetHuman-devantae did not yet indicate what Sling TV should do to make this right.
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