Login to the catalog Admin area, find the order (Listing Orders), and go to that order's information page.
Go to the "Payments" section (click the "Payments" heading to open the section) and find the "PAYMENT LOG" table to determine if the customer has already paid for the order:
Go to the "Status" area in the top-left corner of the page and select the "Cancel Order" option (at the bottom of the list of options, you might have to scroll down to the very last option).
You will receive a pop-up confirmation window: click "Yes, cancel order"
You will be returned to the orders listing.
Note 1: The next time you come to the orders listing, you might not see
any canceled or completed orders by default (unless you have some in-progress orders). You will need to change
the Filter from "Select" to be "All Orders" to see the canceled orders
in the listing.
Note 2: If you wish to see the refunds in your online payment account, you can login to your Bambora (Beanstream) or your other payment account and generate a transaction report to see the details.