Credit cards on my iPad are unavailable

Credit Card details, used for payments, can be stored in potentially three places…

1) For online payments when using the Safari Browser, credit card information is found in the Safari AutoFill settings:

Settings > Safari > AutoFill > Saved Credit Cards

Existing Credit Card entries can be removed by tapping the corresponding entry. Next tap Edit at top-right - and then Delete Credit Card. Adding a credit card is as simple as tapping Add Credit Card - and adding the appropriate details.

2) Payment Card information that is associated with an AppleID account - used to purchase Apps, Subscriptions, Media and services via Apple - are managed from AppleID settings. See:

Change, add, or remove Apple ID payment methods - Apple Support

3) Your Wallet - where you can store Credit Cards registered for ApplePay:

Set up Apple Pay on iPad - Apple Support

You're very welcome.