If you need to do returns or refunds, open the Orders tab:
You can search your orders by clicking on the magnifier button and type the customer name or order number.
Once you found the order, press on this button:
Then select the products that need to be returned:
Press on this button to select the product(s):
Then press on this button to remove the product(s):
Select the following options if you want to restock items and / or refund items:
Finalize the return by pressing on the "Return products" button: