how do i cancel my protection plan on a phone i just upgraded

If you mean Apple Care+, follow the steps here ➡️ Cancel or change the payment method for your AppleCare plan - Apple Support

If you mean something else, please explain.

This article should be helpful about that matter:--> Cancel or change the payment method for your AppleCare plan

Shouldn't be this case, contact Apple Support directly, using this specific link:--> Apple Support

Regards

Giulio

Oops, sorry Phil. I didn't see your reply in time :(

My apologies.

Giulio