Cannot delete file-file used by another process

[aditya_amb]

I want to delete the text file output.txt ,but I get error message. File cannot be deleted used by another process. Can you please help me..I tried close nad flush commands for filestream and stream readers..but did not help..
Here is my code.

Dim chkstr As String
        chkstr = ("usb_download -crc -device VID_" + VIDnum + "_PID_" + PIDnum + " >> output.txt")
        
        Dim proc5 As New System.Diagnostics.Process() 'VID/PID query'
        proc5.StartInfo.FileName = "CMD.exe" '"usb_download.exe"
        '        proc5.StartInfo.Arguments = chkstr

        proc5.StartInfo.WorkingDirectory = "C:\downloadtest\"
        ' proc5.StartInfo.WindowStyle = ProcessWindowStyle.Minimized
        proc5.StartInfo.RedirectStandardOutput = True
        proc5.StartInfo.RedirectStandardInput = True
        proc5.StartInfo.UseShellExecute = False
        proc5.StartInfo.CreateNoWindow = True
        proc5.Start()

        Dim Sw As IO.StreamWriter = proc5.StandardInput
        Sw.WriteLine(chkstr)
        '  Sr.ReadLine()
        ' Dim str As String = Sr.ReadToEnd
        proc5.WaitForExit(5000)






       
        proc5.Close()

        Dim fs As New FileStream("C:\downloadtest\output.txt", FileMode.Open, FileAccess.Read, FileShare.ReadWrite, FileShare.Delete)

        Dim Sr As New IO.StreamReader(fs)
        Dim strtext As String
        strtext = Sr.ReadToEnd
        statustext.Text = strtext
        
fs.flush()
fs.close()
         Sr.close
        Sw.close




        If System.IO.File.Exists("C:\downloadtest\output.txt") = True Then

            System.IO.File.Delete("C:\downloadtest\output.txt")

        End If
        
    End Sub

Thanks in advance for help.