Q: how do i get my debit card off of iTunes

Follow the instructions on the page that you posted from e.g. log into your account via the Store > View Account menu option on your computer's iTunes and select the payment details section, or tap on your id in Settings > iTunes & App Store on an iOS device and then tap 'view Apple id' on the popup and login into it and select payment details.

If you don't get the 'none' option : Why can’t I select None when I edit my Apple ID payment information? - Apple Support