Hy, how do I cancel my payment method to AppStore ?

See the Apple Support article(s) below. 

Apps won’t downloaded.  *

ASC YouTube for what to do if you can’t make a purchase on your iPhone -

App Store, iTunes Store, or other Apple services - If you can't connect   *

Change, add, or remove Apple ID payment methods - Apple Support

See this link on how to remove payment methods.

If you cannot download any apps, is your Apple ID disabled in the App Store and iTunes?

If you see a message that says your account has been disabled in the App Store and iTunes Store, contact Apple Support for help. 

What to do if your Apple ID is Locked or … - Apple Community