Option Explicit

On Error Resume Next

Dim Service
Dim Server
Dim DeleteDate
Dim When

Set Service = GetObject("winmgmts:\root\MicrosoftIdentityIntegrationServer")
Set Server = Service.Get("MIIS_Server.Name='TEST'")

When = DateAdd("m", -1, Now)

DeleteDate = DatePart ("yyyy", When) & "-" & DatePart("m", when) & "-" & DatePart("d", when)

WScript.Echo "Deleting Run Histories from " & DeleteDate

WScript.Echo "Result: " & Server.ClearRuns(DeleteDate)

Sub ErrorHandler (ErrorMessage)
  WScript.Echo ErrorMessage
  WScript.Quit(1)
End Sub