To hide any user account from Windows login screen, make following registry changes:

• Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList
  SpecialAccounts and UserList keys are not present by default – you need to create them yourself.
• Inside UserList key create a new DWORD type entry
  name: user account login name (the one you want to hide)
  value: 0
• Restart the PC

I haven’t tested, but I believe the same instructions should work in Windows 7.

05.2015
Windows 8.1