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You should notice that when an order is edited, its reference is displayed in the Map Header. 
Even if you have clicked Cancel on the order details pane, the order information stay in the application memory to allow you to add new restrictions to this order. If you wish to completely remove an order from the editing session, please click the Edit tool again. Now you can see that there is another button below the list of existing orders called End Editing.
When you press this button, the current order will be removed from editing session. The easiest way to check whether it happened is to look at the map. The information about edited record should be removed from the Map Header.