Opening an account with Apple's iTunes allows you to buy and download music tracks, movies and TV shows from the iTunes Store direct to the iTunes media library. Each time you buy an item, iTunes automatically bills a credit card or debit card with the transaction. If you have an iTunes account and want to remove the registered credit card you use to fund your iTunes purchases, you'll need to access your account settings and edit your payment information.
Launch iTunes by double-clicking its program icon on the desktop.
Click "Store" and then "Sign In" from the program menu.
Enter your user identification and password into the login boxes and click "Sign In."
Click "Store" and "View My Account" from the menu.
Enter your password again and click "View Account." This opens the "Apple Account Information" page.
Click "Edit Payment Information." This displays the list of accepted payment options and includes your current credit card details.
Click the button for your preferred payment option to replace the credit card or, if you don't wish to include a payment option, click "None." This will remove your credit card from iTunes.
Click "Done" at the bottom of the page.
Selecting the "None" payment option means you will not be able to download items from the iTunes Store.