Hmm. I've been in that section of the website and there isn't an option to cancel the order. I think I'm going to have to call or email in order to cancel the order.
EDIT: This is from their FAQ section. It looks like I'm stuck. >_<
How do I edit/cancel an order I've just placed?
IMPORTANT NOTE: You will only be able to do this if your order has not yet shipped or has not completed payment processing. From the “Your Account” screen, select one of the available options:
•Change Shipping Address
•Change Billing Address
•Change Payment Method
•Cancel Items or Orders
Find the order you’d like to edit and click “View or Change Order”. From here, you may edit your shipping/billing address, payment method, cancel individual items, or entire orders… but it would be nice if you didn't do those last two…