How to Remove Credit card info on iTunes?

You can't, you must always have a valid credit card in your account.
All you can do is replace it with a different card.

Cartmen979 wrote:
hi, i would like to know how to remove my credit card info. because I used a prepaid master card and now I owe money so I want to take the credit card off.
and for some reason the "None" option isn't there any more.

Yes you can remove it. However, as Forum member Katrina S discovered, you cannot remove an expired credit card. So first update to a valid credit card. Then the "None" button will again appear, and you can remove the card altogether.

Actually, I think Chris or Dave originally suggested that - entering a valid card, then switching it to none. It was a bright idea, but I don't think it was mine!