Canceling an optional premium network subscription like HBO (Max) through Comcast Xfinity requires navigating the account management options on your Xfinity set-top box interface, logging into your online Xfinity customer portal via a web browser, or contacting Comcast customer support directly. Users can go to the TV and streaming section of their account settings, select the active premium channel subscription, and follow the automated on-screen prompts to confirm the cancellation and prevent future monthly billing charges.