Hide a user from GDM Logon Window

1. 

# vim /etc/gdm/custom.conf

2.  Hide some users

{

[greeter]

Exclude=user1, user2

}

Hide All

{

[greeter]

IncludeAll=false

}

3. save

--------------------Reference---------------------

1. http://www.fedoraforum.org/forum/showthread.php?t=246103