You can cancel pending trades which have not yet been executed. 

For example: trades which have been made outside of market hours, or limit orders which are yet to be executed. 

• To see your trades which have not yet been executed, select the account in which the trade has been made.
• Switch the table to view Orders.
• Orders which can be cancelled will have the word Cancel in the Options column. You can click on Options to arrange your trades by whether you can cancel them. 
• Click Cancel for the trade that you wish to cancel. 
• You will then be shown a detailed summary of the order. 
• Click on Cancel Trade to confirm.  

After you have requested cancellation, the order’s status will change to Cancel Pending. 

The order may have been in the process of being executed when you requested cancellation. It is not confirmed as cancelled until the status changes to Cancelled.

If your trade is cancelled successfully, you will not be charged any trading fees for the order.