How do I reverse a a payment entered against an invoice that was not paid and entered in error?

Welcome to the Community space, Helen. I appreciate your commitment to getting things right in your QuickBooks Online (QBO) account. Let's go through the process of correcting an incorrectly recorded payment against an invoice.

To begin, there's no need to delete and re-enter the invoice. You'll only need to void or delete the incorrect payment applied to it. This process will change the status of your invoice back to open (unpaid), reversing the payment.

Here's how to locate the payment and undo it:

1. Log in to your QBO and go to the Sales menu.
2. Navigate to the Sales transactions tab.
3. Use the filter options to streamline your search for the specific invoice payment.
4. Pick the Money received option to view all payments.
5. Locate the payment in question and click the drop-down arrow next to the View/Edit option.
6. Choose either Void or Delete as appropriate.

You may also refer to the screenshot below for visual reference:

These steps will undo the incorrect payment. You'll then be free to record it against the intended invoice. 

Tap the Reply button below if you have any other QBO-related concerns. I'm always here to guide you through the program's features, ensuring you have the tools to make well-informed business decisions.