If you need to reverse a transaction that was originally paid with a check because it was a mistake for example, this is how to reverse it:
Open up the Invoice that you need to reverse.
Press the "3-dot" button next to the items you need to reverse and choose Reverse.
Press the Checkout button once you have reversed all the necessary items.
Press the "Check" tab within the shopping cart area.
Select the check type "Regular Check". Enter in the same check the customer originally paid their invoice with.
Make sure you have the correct person showing as "Invoiced" and that the Check Amount box has the same negative amount as the shopping cart does.
NOTE: Not all employees will be able to see the "Amount" box at the bottom of the page. You must have Customer Credit authority in Employee Authorizations.Choose whether or not you want to e-mail the receipt to the customer. Uncheck the box if you do not want to send them a receipt.
Write a payment note under the "Add Note" section, saying what happened.
Hit the "Process Checkout" button when ready.