If you haven't confirmed your order, you can still remove the combinations you've subscribed. You have two ways to do this. The first one is by going to your current order by clicking on 'shopping cart' at the top left of the screen and then on 'view cart' or by clicking on your name on the top right and then on 'orders'.
You'll see an overview of your current order. Besides each row, you'll see a link to change or remove a combination. The second way is to navigate to the course you've entered and click on the change or remove link besides your start number.

If you have confirmed your order, the only way the change it, is to contact us.