If the order or the item(s) that you want to cancel have not been shipped yet, you can cancel the order directly through your "Order" section.
If you have placed the order as a guest, signup/sign in with the email that you have used while placing an order and you can then cancel order through "Order" section.
In such cases, the order will be cancelled and the money will be refunded to you within 48 business hours after cancellation.