$path = 'C:\test'
$acl = Get-ACL -Path $path
$acl.SetAccessRuleProtection($True, $True)
$acl | Select -ExpandProperty Access |
    Where{ $_.IdentityReference -eq “LTCAHJ\Guest” } |
        ForEach{ $acl.RemoveAccessRule($_) }

Set-Acl -Path $path -AclObject $acl