Ciao, perchè dopo il download forzato del file, non riesco a cancellarlo dal server?

Grazie per i suggerimenti e buona pasqua a tutti.
codice:
<%
        Set oFso = CreateObject("Scripting.FileSystemObject")      

        sSourceFile = "D:\Inetpub\wwwroot\public\test.pptx"
        sDestinationFile = "D:\Inetpub\wwwroot\public\test_ " & Session.SessionID & ".pptx"

        oFSO.CopyFile sSourceFile, sDestinationFile

        strFilePath = sDestinationFile

        Set oFile = oFso.GetFile(strFilePath)
                
        strFileName = UCase(oFile.Name) 
        strFileSize = CLNG(oFile.size) 
        
        Set oFile = Nothing 
        Set oFso = Nothing 

        Const adTypeBinary = 1 

        Response.Clear 

        Set objStream = Server.CreateObject("ADODB.Stream") 
        objStream.Open 
        objStream.Type = adTypeBinary 
        objStream.LoadFromFile strFilePath 

        strFileType = lcase(Right(strFileName, 4)) 
     
    Select Case strFileType 
        Case ".asf" 
            ContentType = "video/x-ms-asf" 
        Case ".avi" 
            ContentType = "video/avi" 
        Case ".doc" 
            ContentType = "application/msword" 
        Case ".zip" 
            ContentType = "application/zip" 
            ContentType = "application/x-zip-compressed" 
        Case ".xls" 
            ContentType = "application/vnd.ms-excel" 
        Case ".gif" 
            ContentType = "image/gif" 
        Case ".jpg", "jpeg" 
            ContentType = "image/jpeg" 
        Case ".wav" 
            ContentType = "audio/wav" 
        Case ".mp3" 
            ContentType = "audio/mpeg3" 
        Case ".mpg", "mpeg" 
            ContentType = "video/mpeg" 
        Case ".rtf" 
            ContentType = "application/rtf" 
        Case ".htm", "html" 
            ContentType = "text/html" 
        Case ".asp" 
            ContentType = "text/asp" 
        Case Else 
            ContentType = "application/octet-stream" 
    End Select 
     
    Response.AddHeader "Content-Disposition", "attachment; filename=" & strFileName 
    Response.AddHeader "Content-Length", strFileSize 

    Response.Charset = "UTF-8" 
    Response.ContentType = ContentType 
     
    Do While Not objStream.EOS 
        Response.BinaryWrite objStream.Read(8192)
        Response.Flush 
    Loop 

    objStream.Close 
    Set objStream = Nothing
          
    if oFso.FileExists(sDestinationFile) then
       oFso.DeleteFile(sDestinationFile)
    end if
    
    if oFso.FileExists(sDestinationFile) then
       oFso.DeleteFile(sDestinationFile)
    end if    

    set oFso = nothing
       
%>