Q: bank details

Select None for payment method >  iTunes Store: Changing your payment information

Why can’t I select None when I edit my Apple ID payment information?

One caveat to Carolyn's response..... You do have to enter bank details unless you followed the very specific way to create an AppleID the correct way so that you do not have to enter bank details. Otherwise, you have to enter the payment method then you should be able to remove the bank card.

It is too late now if you already created an Apple ID, unless you want to set up another emails address. Read this for the information.

Create an iTunes Store, App Store, or iBooks Store account without a credit card or other payment method - Apple Suppor…