How to remove card on file

Open the Wallet app, tap on the card, then the 3 dots in upper right corner, then Card Details - Remove Card

Presumably you have a different card you’re planning to use.

Set up Apple Pay - Apple Support

Once that new card is in place, tap the old card in Wallet, then tap the three dots in the circle in the upper right, choose “Card Details”, then “Remove Card”.

This link should help...

Remove a payment method from your Apple ID - Apple Support

The link in blue above your name on this page will tell you how to add a card should you also need that info.