Call AT&T customer service at 1-800-331-0500 for wireless or 1-800-288-2020 for internet, TV, or phone
Use the myAT&T app or sign in to your AT&T account online
Navigate to the cancellation or account management section
Request service cancellation and confirm the cancellation date
Return any AT&T equipment, such as gateways, receivers, or modems
Ask for a return receipt or confirmation number
Pay any final balance or early termination fee, if applicable
Keep the cancellation confirmation for your records