If a discount has been applied to an order and needs to be removed, you can do so by deleting the discount directly from the order itself. See below for more information.
Discounts applied to an order will display in blue, as you see above with the INDUSTRY discount. Clicking on the discount will open up additional product pricing and discount details. Here, you can delete the discount by clicking the X REMOVE button in red.
Once removed, the page will update without the discount shown. After exiting out of the page, you will be brought back to the order screen where you will see that the discount is no longer applied.