上網找到方法
-----
# This will delete declined updates in a WSUS server.

# It can be done in less lines, however there is a chance in poorly maintained WSUS servers of an SQL timeout.
# Doing it in this way allows even partial runs to remove some data, so subsequent runs have more chance of succeeding.

[reflection.assembly]::LoadWithPartialName("Microsoft.UpdateServices.Administration")
$wsus = [Microsoft.UpdateServices.Administration.AdminProxy]::GetUpdateServer();
$ListOfUpdates=$wsus.getupdates() | where {$_.isdeclined -eq $TRUE}
$listofupdates | measure | select count
foreach ($UpdateToDelete in $ListOfUpdates) {
$wsus.DeleteUpdate($UpdateToDelete.Id.UpdateId.ToString()); Write-Host $UpdateToDelete.Title removed }
$ListOfUpdates=$wsus.getupdates() | where {$_.isdeclined -eq $TRUE}
$listofupdates | measure | select count
-----