Closing an order can be done in one of the following ways:
Double-click the order you want to close in the Trade tab (in the Terminal area), then click the Close By Market button.
Right-click your order in the Trade tab, select Close Order, and confirm it. With One-Click Trading active, the order closes when Close Order is selected.
Click the X on the right of the order in the Trade tab; this closes the order instantly with One-Click Trading active.