If you create some local user accounts in Windows for providing some services, but don’t want to let them show in Welcome Screen. You can add some settings in Windows Registry.
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList] "cyg_server"=dword:00000000
I have tried this in Windows 7 and Windows 2008 R2. It works.
Google reference: “Hide Users on Welcome Screen in Windows”.