Before we proceed to explain how to cancel a pending order, kindly ensure that you are using Google Chrome.
The steps are:
1. Log in into your account and select the buy/sell tab on the menu of the exchange.
2. Select the market in which you placed the order (for example, BTC/USD).
3. Under "My pending orders" click on the order that you would like to cancel. An alert will appear asking if you are sure you want to cancel, proceed to click OK to cancel the order.