You want to add or remove permissions for users to have active sync privileges.
This is done via the MyExchange Control Panel.
- Once in, click on Active accounts and click login next to the account you want to change active sync permissions on.
- Next Click On Active Sync.
- Click Enable active Sync For Users.
- Finally, Just click on the user you want to change and then add or remove as needed by checking or unchecking active sync for that user. Once done click proceed and you are done.