To modify or delete a pending order that you have placed, click on the ‘Orders’ tab in the ‘Trade Watch’ window.
This will present all your pending orders.
Right-click on the order you wish to modify or delete, to be given the option to either modify or cancel the order.
If you click on ‘Modify’, a new window will appear that will allow you to change the parameters of your pending order. If you click on ‘Cancel’, your order will be automatically removed from the list.
You can also Cancel All orders, or simply click the 'X' button to close a specific pending order.