If you are not deployed you simply need to go to your local education center and speak with a counselor to change your degree plan.
If you are a GoArmyEd student you can login to the site, create a HelpDesk case and select "degree plan" in the drop down box. In the message simply state which school you want to be your home school and which degree plan you want to follow.
If you are deployed to Iraq you can send your new degree plan request (or change of home college) to email@example.com. You will receive an immediate automated message and a real response within a few days. You'll see the change on your GoArmyEd homepage as well.