How to remove my card info from my iPod?
You want to remove your card info from your Apple ID. You can do this from your iOS device or from iTunes on a Mac or PC.

This article has step-by-step instructions to get to the page where you can edit your payment information.

https://support.apple.com/en-us/HT201266

If you are trying to remove your card when you are being prompted to update your card info, it may not work. Instead, follow the step-by-step instructions from the Settings app.