If you need to cancel a Marketplace order you have placed, follow these steps:
Head to your "Orders" page from the main menu of shef.com (top left corner)
Choose "Upcoming" from the tabs at the top of this page
Click the price of the order you are wanting to cancel
Scroll down past the price breakdown to find the "Cancel Order" button
Click "Cancel Order" and confirm any prompts that pop-up.
Keep in mind, if you do not see the option to cancel your order, then your order may be past the cutoff time and can no longer be cancelled since your shefs have begun preparing for your upcoming order.