How to void cash payments

Go to the launch screen and click on orders.
Click Open orders (this button is in the top middle) This will switch it over to closed orders.
Double click on the table you just closed. It is typically sorted by time so it should be the last table in the list.
Select the completed payment.
Select void payment to cancel the payment.
Select yes to delete the payment and reopen the table.
The terminal will bring you back to the payment screen of the order. It will show that the total is due.