Orders that are delivered cannot be edited from the Order List, they can only be edited in the Dispatch Board. If you cannot find the order on the Dispatch Board, you can still view the order by adding /orderno at the end of the dispatch board URL where orderno is the order number you are looking for.
The URL would then have this format: https://xxxxxxx.dsapp.io/fulfillment/#/orders/A12345
where xxxxxxx.com is your Dispatch Science URL and A12345 is your order number.