I want to remove my payment card ?

No you have any subscriptions like Apple Music, Apple One, Apple TV+, or any third party subscriptions like Netflix, Hulu, etc.? Are you an organizer for Family Sharing? If so you must have a credit card on file.

Go to Settings -> Apple ID (top) -> Payment and Delivery. Select the card you want to remove.

As anypats mention, you can not remove your card if you have an active subscription, such as Apple Music, or extra space on iCloud, you first have to unsubscribe from it.