By default the Administrator account in Vista is Disabled – everything is run in a sudo fashion without actually logging in to the Administrator account. Some times due to external password recovery systems or other various reasons the built-in Administrator account is enabled, causing it to show up on the Welcome Screen.
In order to stop the Administrator account from showing as a login option on the Welcome Screen in Windows Vista you need to set the Administrator account to not active with the
net user command from an Administrative
cmd prompt as follows:
net user Administrator /active:no
Some people report that the “/” causes the command to fail, try it without:
net user Administrator active:no
From then on the the Administrator account should no longer show on the Welcome Screen.