The root administrator username is stored in the neo-security.xml file. It is an alphanumeric string value to the admin.userid.root setting.
After changing the root administrator username, the ColdFusion 8 Administrator login screen will still display the default value admin in the User name field. If single password authentication is enabled, pressing the Login button will simply submit the root administrator password. If separate username and password authentication is enabled for the ColdFusion 8 Administrator, the new username will be able to log in successfully (using the root administrator password), and the default admin username will fail.