It is not possible to remove a credit card from an account, though you are able to add or update a payment method.
To prevent account deactivation and ensure prompt payment, a valid card must be added to each Mapbox account. The card added to your account will be automatically charged when the Upcoming invoice is finalized based on that period of service usage.
Please note that if an account does not have a credit card on file, Mapbox will not be able to verify account ownership. In this case, the only next step will be to create a new Mapbox account and add access tokens from your new account into your map implementations.