There are a couple of reasons why you might not be able to remove your credit card, bank account, or PayPal payment method:
Active Paid Subscription: If you have an active paid subscription with Rebrandly, you can't delete your only payment method. You will need to cancel your paid plan. See How do I change or cancel my Rebrandly subscription?
Auto-Renewing Domains: If you have at least one branded domain with auto-renewal enabled, you can't delete your only payment method. To remove the payment method, first turn off auto-renewal for your domains. See How do I turn off auto-renew for my domain purchase?
Once a payment method is deleted, it cannot be retrieved and would have to be re-entered.