Please note that you will not be able to completely remove an order. However, you will be able to cancel it and this will prevent your from seeing it in the queue. You can cancel orders both in your Appath account and your Shopping Cart / marketplace.
Cancelling an order will only change the order status to Cancelled. But please note that this status will not be reflected in your Shoping Cart / marketplace. In order to fully cancel an order, you will need to go to your Shopping Cart and cancel it over there. However, as soon as an order is cancelled in your Shopping Cart / marketplace, it will automatically get cancelled in your Appath account.
In order to cancel an order in Appath, simply locate the order, select it and click on the Cancel button at the top: