You can delete the incorrect payment by navigating to the Sales transactions window, Playawest45.
Before we begin, can you please clarify how you've received the "hidden" message when opening the invoice? Providing full details or a snapshot about this matter can help us relay a precise resolution regarding your concern.
If the "hidden" notification shows up this way:

It indicates that the Amount paid value is only visible on your end and is unavailable once you send or print the invoice. But, this detail will appear on your sales records or reports within QuickBooks.
On the other hand, here's how you can delete an invoice payment:
- Go to the My apps menu, then the Sales & Get Paid tab.
- Navigate to Sales transactions.
- Modify the transaction Type as Money received.
- Enter the payment Date and the Customer if needed.

- Locate the entry and click its designated dropdown arrow beside the View/Edit option.
- Click Delete.

- Confirm the action by ticking Delete again.
If you need further assistance or meant something else about the hidden message, kindly add a reply below.