When you delete an invoice that has a payment applied to it, the payment
stays on your books. The funds remain in your bank account or in Undeposited
Funds, but the payment no longer has an offsetting invoice.
If your customer is returning goods purchased on an invoice, don't
delete the invoice. Instead, create a credit memo for the invoiced items. If
the customer wants a refund, create a credit memo and write a refund
check. Don't delete the invoice.
If you applied the payment to the wrong invoice, don't delete the
invoice; follow the procedure for reapplying the payment to a different
Handle refunds and returns
Delete a deposited
Void or delete