How can I remove my payment info?

Alright so I downloaded this app and afterword I tried to download some books on iBooks. It said there was a problem with my billing information. Because this has happened in the past I knew what the problem was and put money in my card. The new problem is that the app was already processed and it went through but now it says that my card type isn’t support when I click the option none. I thought my app payment didn’t go through but it says it has therefore I don’t know what to do.