This can be done through your website. You must first log in to do so.
1. Log in
2. Click 'E-commerce' tab on the black bar at the top of your screen
3. Hover over 'Transactions' then select 'Transactions List'
The page that loads is a list of all the transactions that have taken place on your website. From here you can edit, delete and update them.
Please see the attached document for further instructions.