The POS software has a Refund Mode which works exactly the same as Sales Mode but in reverse.
The use of Refund Mode can be restricted by clerk using the clerk setting - Allowed Modes.
To use Refund Mode:
From the Home screen select Refund Mode.
The sales screen now appears but you are now in refund mode.
When you are in Refund Mode, you will see the text REFUND in the menu bar top right.
Sign on with a clerk that has access to Refund Mode.
"Sell" the products (they will appear with a minus sign in the reg window) that you want to refund and then finalise the sale with the appropriate method of payment.
IMPORTANT - When you have finished your refund, make sure that you go back to the home screen and select Sales Mode
When you are in Sales Mode, you will see the text REG in the menu bar top right.