Authenticated Users removing via Powershell

#REFERENCE NOTE: Below was provided using Tome's Land of IT. I did a slight modification (http://powertoe.wordpress.com/)#

PS C:\> [ADSI]$power="WinNT://50NV9S1-E6520/Administrators,group"

PS C:\> $power.Remove($NT AUTHORITY\Authenticated Users)

ERROR:

Exception calling "remove" with "1" argument(s): "The trust relationship between this workstation and the primary domain failed.

"

At C:\Users\schetry\AppData\Local\Temp\9a82b494-1fce-414b-9d02-465305152294.ps1:2 char:14

+ $group.remove <<<< ("WinNT://$env:NT AUTHORITY/Authenticated Users (S-1-5-11),user")

    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException

    + FullyQualifiedErrorId : CatchFromBaseAdapterMethodInvokeTI