How to remove a Distribution Point from a Boundary Group

$BoundaryGroup = "New Boundary Group"
$DistributionPoint = "Server"
$DomainName = "CM.LOCAL"
$SiteCode = "PS1"
$NALPath = "[""Display=\\" +  $DistributionPoint + "." + $DomainName + "\""]MSWNET:[""SMS_SITE=" + $SiteCode + """]\\" + $DistributionPoint + "." + $DomainName + "\"
$BoundaryGroupQuery = Get-WmiObject -Namespace "Root\SMS\Site_PS1" -Class SMS_BoundaryGroup -Filter "Name = '$BoundaryGroup'"
$BoundaryGroupQuery.RemoveSiteSystem($NALPath)