I'm not sure if any of the people in this thread are talking about ordering the PC version of MEA but here's how to cancel the MEA preorder for PC:
Check the status of your refund in your Order History on the order summary page.
1. Log in to origin.com
2. Select My Account and then Order History.
If your refund doesn’t appear in My Cases, and the processing time for your payment method has passed, contact us so we can help you out.
I went to "Order History," then adjusted the setting to orders I'd placed in the last 6 months. MEA's order came up so I clicked the "+" sign next to it and then clicked "Cancel Order."
That was all I needed to cancel. I'm not sure what the procedure is for canceling a preorder on a console but it can't be that much different.
Try this if you you need extra help:
Request a refund right here on EA Help. You’ll be able to see if your games are eligible for the Great Game Guarantee. If you have games that qualify for a refund, you can complete and submit the refund request form.
Hope this helps someone!
P.S. VIONOVA, if this helps you, please mark my post as the answer so the question will be closed. Thanks!