Kevin, the only way you can cancel your service is by calling. There are several things they must ask you to verify that it is really your account, and other legal conformations.
I think you should tell us what you feel is so bad about Exede. It is satellite internet, and has some draw backs, but is aimed at those of us who have no other internet providers serving our area. It is not a good choice for anyone who has access to a ground based ISP.