You are able to Cancel an Open order if you have not accepted any payments. When you cancel an order it will override your cart and scheduled events and payments (deletes them).
When you are in an order, go to your Manage Tab > Job/Order Settings and you will see an option to "Cancel" and you will have to provide a reason as to why and then hit the Check Mark! Remember, it will not allow you to Cancel the order if you have any payments accepted! You will have to Refund them to bring the balance back to the orders total.
When you are in this order you will be able to see when you had scheduled the events for and also them items you had in the cart. You will not be able to see these on any reports or on the main calendar.
You can find your Cancelled Orders by going to the Order List and filtering by Order Status!