In the trading page, under your "My Open Orders" section, you will find the cancel button. If the order is still not filled or completed, select “Cancel” and confirm to cancel the transaction.
Another way is to go to the "Orders" section of your account and select "Open Orders". If the order is still not filled or completed, under "Cancel", select “Confirm” to cancel the transaction.
Once done, your frozen digital asset will be sent back to your account.