If you placed an order on the order book and want to cancel it, please follow the steps below.

Step 1: From the home page of your Quidax app, tap on the arrow button (as shown in the image).

 Step 2: Select Order Book.
 

 Step 3: At the top left, tap on the market pair.

 Step 4: Navigate and select your preferred market pair or the market pair you placed the trade on

Step 5: Locate the order you want to cancel and tap on Cancel.

Voila, cancellation is done!