How do i cancel apple care

See instructions in: How to manage your AppleCare plan - Apple Support

If you are paying monthly for AppleCare, see the following from the previously provided link:

If you don't see your plan, finish setting up your account online, then you'll be able to manage your plan and how you pay for it.

If your AppleCare plan still isn't listed with your other services, or if you need more help, contact Apple Support.