Passport is a membership provided by your local station. For security purposes, only your station has access to your membership information and billing.
Because memberships are retained at a local level, you must email or call your local station in order to cancel your Passport member benefit.
You can also visit your local station's website for more information on how to contact them. If your station sent you an email confirmation thanking you for your gift, this email also should have had information on how to contact your station.