You can easily cancel your order by following these steps:
1. Go to the 'Market' or 'Trade' or 'Futures' or 'Derivatives' menu, then click on the 'Orders' button
2. Select the 'Open' order, then click on the transaction you wish to cancel
3. Click on the 'Cancel Order' button to complete the process
*You can only cancel orders that have not been fully matched. If some portions of the orders have been matched, you can cancel only the remaining unmatched portions. The matched portion will already be converted into funds or Cryptos in your wallet as usual