How to cancel my AppleCare+ for an iPhone?

Follow the steps outlined in the support document posted below to cancel Apple Care+.

click here ➜ Cancel or change the payment method for your AppleCare plan - Apple Support

If you don't have an Apple device logged in to the Apple ID that holds the Apple Care+ subscription, then contact Apple support directly by clicking here ➜ contact Apple Support

If the AppleCare+ coverage was acquired for a phone two years ago, it will have expired by now and you need not worry about it anymore.

Visit getsupport.apple.com and review your registered products list to confirm the expiration of the coverage.