How to cancel mobile service

Hi,

I am trying to cancel my Xfinity mobile service. Just that, I don't want to transfer a number to a new service, I don't want to unlock a phone. The app/website supplies directions for doing those things but not for canceling the service without doing those things. The directions for transferring a number to a new carrier direct you to the devices tab on the account page, which is the first step towards canceling an account via that route but there is no device associated with my account. That is one of numerous reasons why I want to cancel, which I can't because Xfinity keeps you stuck in this Escher-esque recursive customer service loop that prevents you from canceling the service.

Even better: Here comes the part where you tell me you can't do anything for me here and provide a number for me to call or a chat link to click. I called that number already. I tried chat. They told me they can't cancel the service, I have to do that through the app. Which doesn't let me cancel the service. 

Now what?