You can make a payment method inactive instead of deleting them in QuickBooks Online (QBO). Let me guide you on how to do this task:
Go to the Gear icon.
In the Lists section, choose All Lists.
Select Payment Methods.
Click the drop-down icon that is aligned with the name.
Select on Make inactive.
Here's an article for more information about changing your payment information in QBO. This article is for QuickBooks Online Global version and can be applied to all QBO versions: Update the payment information for your subscription.