How do I remove a credit card if it is being used?

I don't have another payment method...

Try and add a new card and then remove the other card to see that works.

If not contact support.

You can also contact MS Live Support if you need further assistance.

Add another payment option/type to replace that one.

Payment options include:

• Credit cards, including prepaid credit cards
• Debit cards (not available in all regions)
• PayPal (not available in all regions)
• Mobile operator billing (not available in all
  regions)
• Direct debit (Germany only)

Note You can update payment options for both purchases and subscriptions on your console; however, the steps are slightly different. For subscriptions, see

Update an Xbox subscription for you or your child.

Add a payment option

1. Press the Xbox button
    to open the guide.
2. Select System > Settings >
   Account > Payment & billing.
3. Select Add a payment option.
   
4. Choose a payment option, and then follow the instructions.
   

Update a payment option

1. Press the Xbox button
    to open the guide.
2. Select System > Settings >
   Account > Payment & billing.
3. In the box that contains your current payment option, select
   Edit info.
4. Update your payment option details, and then select
   Save.

Remove a payment option

Note Payment options used to pay for a subscription can be edited, but they can't be removed until you add a new payment option.

1. Press the Xbox button
    to open the guide.
2. Select System > Settings >
   Account > Payment & billing.
3. In the box that contains your current payment option, select
   Remove.
4. Select Yes, remove to confirm payment option removal.

You can't remove a card while it's being used. Since a payment was declined, it sounds like you would need to add a new card first. You can try doing so at http://account.microsoft.com and
if not, you'll need to contact support and speak to billing. http://support.xbox.com/contact-us