changing the credit card for icloud subscription

Re: "how can I change the credit card for icloud subscription"

Your Apple ID is the account you use to access Apple services like the App Store, Apple Music, iCloud, iMessage, FaceTime, and more. It includes the email address and password you use to sign in as well as the contact, payment, and security details you use across Apple services.

Check which payment methods Apple can accept in your country or region:

Payment methods that you can use with your Apple ID - Apple Support

Because you have an active subscription, you will likely need to add a card before you can delete one.

See: What to do: If you need to change or update your Apple ID payment method - Apple Support

or

How to Add an Apple ID Payment method: Add a payment method to your Apple ID - Apple Support

and

How to delete an Apple ID payment method: Remove a payment method from your Apple ID - Apple Support

You may need to allow 24 hours for updates to come into effect.