I can see how convenient it is to have a way to delete your customers' banking information, S4lly. Let me share some alternatives to aid your concern.

You're correct that you only have the option to replace it or merge it with a new customer account without banking details in QuickBooks Online (QBO). Since you don't want to replace the information, you'll want to merge it with a new customer. 

Let me show you how:

1. Create a new customer account.
2. Enter the same information as the original customer account except the Payment and billing info.
3. Add 1 to the name in the Display name as field. Select Save.
   • Original customer account - John Hale
   • New customer account - John Hale1
4. Rename and merge the original customer account with the new one. Then, tap Save.
5. On the confirmation window, select Yes to merge the accounts. It'll delete the original customer account with the credit card info appearing in the deleted customers list.
   
   
6. Rename the merged customer back to the original one.

While this feature is unavailable, I recommend sending your feedback to our Product Development Team so they can review it and consider implementing it in the future. Here's how:

1. Go to the Gear icon at the top and select Feedback.
2. Enter your comments or product suggestions.
3. Click Next to submit feedback.

Also, see this article if you need further guidance with transferring the administrator access to another user: Change the primary admin user in QuickBooks Online.

Additionally, you can check out this article to review the recorded sales transactions and their statuses in the Sales menu: View sales transactions.

If you have further questions about managing your customers in QBO, just let me know by leaving a comment below. I'm always here to help.