How do I cancel this unwanted and unused service? Despite there being a "Manage Your Plan" button, it doesn't really work. Online chat does not either. Of course, if you want to add a service, you can do that all day online. You just can't cancel one or change your plan if it means stopping another service.
As far as I can tell, Comcast doesn't really have a pick and choose type of service.
I'm assuming that because they change their packages around a lot and usually get subscribers for 'intro' rates based on the package, they can't really price it out on a per item deal.
The only option they provide is that you have to choose yet another package that contains the items you want.
e.g. If you are on a triple play and want to drop telephone, you have to choose a current double play package.
The current package may actually have less options that what you currently have and you'll find your savings aren't that much if you need to keep those same items (e.g. Starz was free with my current package, but if I get a new one, I'd have to pay for it separately).
It's really like buying a car.
You want the fancy radio, but you can't get it unless you also upgrade to heated seats and a moonroof.