hide postgres user from the login screen – (tested on windows 7)

Run the commandline as administrator.

Steps:

Type cmd on the search box, right click on the cmd icon and Run as administrator.

Then copy and paste command below:

REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList" /v postgres /d 0 /t REG_DWORD /f

original post here.