1. Click the invoice that you would like to remove the payment from.
2. On the edit invoice screen scroll down till you see "Invoice Payments."
3. Click Do Not Apply to This Invoice then click Save.
If the invoice was fully paid then the invoice will now be moved to the Open Invoices section of the ledger.
The payment that was removed will appear under the Unapplied Payments/Credits section in the client's Ledger. You can now apply this payment to a different invoice if you wish or you can leave it there till you're ready to bill the client again.
Deleting the Payment
If you want to fully delete the payment then click Delete next to the payment in the Unapplied Payments/Credits section. This will fully remove the payment from the ledger.