how to delete a payment in quickbooks

Glad to have you back here in the Community, @anchorgraphicsof.

You'll need to recreate the invoice that has been deleted to record your transactions accurately. Just visit the Audit Log on your QuickBooks to view the details of the invoice.

To do that:

Go to Gear icon at the top⚙ and selectAudit Log.
HitFilter.
Use the fields on theFilter panel to choose the appropriateUser,Date, orEvents filter to narrow the results.
Click onApply.

After checking the invoice's information, recreate it. Please see this link for reference: Create invoices in QuickBooks Online

Just a reminder, if you want to undo a payment attached to an invoice on your future transactions, all you have to do is to unlink it. This way, the invoice will be open again and the payment will show as credit.

To do that:

ClickSales from the left pane.
Select theCustomerstab and choose the customer's name.
Open the invoice that has been pay and click on the1 payment madelink at the top.
Remove the checkmark on the invoice to detach the payment.
HitSet as a creditwhen a pop-up window prompts.

Please see the sample snips below for visual reference:

To learn more about receiving payments and applying credits in QuickBooks Online, please see these links below:

Handle a customer credit or overpayment
Record invoice payments in QuickBooks Online

I got you covered if you have any other concerns. I'm always available to help. Have a lovely day!