If you've entered an enrollment request and need to cancel it, you can from the Continue Unsubmitted tab. Simply click on the Cancel button under Actions and it will be removed from your list.
If you would like to review the enrollment requests that have been canceled on your account, you can see them by using the status filter. Just select Canceled and click Search. Any canceled requests will display.
There is an option to resurrect the request by clicking on Continue, but it will bring you back to the beginning to submit the request from the beginning.