Support: Remove Credit Card From iTunes
FAQ: How to remove a debit or credit card from your iTunes account.
A common scenario may be that you wish to allow kids to download free apps on an iPod or iPad but want to lock up “in-app purchases” or prevent “paid for” apps from being downloaded.
Here are the steps to remove your bank details from the account.
1. On a PC or Mac – sign in to your Apple Account through an internet browser using your Apple ID & password.
2. Once you are signed in. Click on your Name and the link to Account Info.
3. On Payment Type, click Edit. From here you should have the option to change to None.
Tip: If you ever have difficulty removing your bank card details from any type of online account, instead of removing the card, edit the details (ie. change the card numbers around to something random). Payments will automatically reject in future.
Some online services make things incredibly difficult when you decide you want to remove your “default payment” method for their service. So go for edit and scramble the numbers.