I need to cancel my iTunes account

Are you going to change your Apple ID?

Read this support guide:

Change your Apple ID - Apple Support

if you get no help, you can contact Apple Support using this link:

Contact Apple for help with Apple ID account security - Apple Support

Regards

Giulio

You can’t cancel an Apple ID/iTunes account. You simply stop using the ID. If that’s what you want to do, remove your credit card details from the iTunes account and just stopping using it.