Завершить процесс, открывший книгу Excel

Private Sub хххххToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles хххххToolStripMenuItem.Click
        Dim myProcess As Process = System.Diagnostics.Process.Start("C:\Users\Kolgushkin.ev\Desktop\Проги\Календарь\Календарь_\Календарь_\Resources\Календарь на 2014 год ххххх.xlsx")
        If (Me.хххххToolStripMenuItem.Checked) Then
            myProcess.Start()
        Else
            myProcess.Kill()
        End If
    End Sub

    Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
        If CheckBox1.Checked = True Then
            Process.Start("notepad")
        Else
            Process.GetProcessesByName("notepad")(0).Kill()
        End If
    End Sub

Imports Microsoft.Office.Interop
 
Public Class Form1
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim ExcelApp As New Excel.Application
        '...
        ExcelApp.Quit()
    End Sub
End Class

'    Dim ExApp As New Application                               'Приложение Excel
'    Dim ExWB As Workbook                                       'Книга Excel
'    Dim ExWS As Worksheet                                      'Лист книги Excel
 
    Private Sub frm_Main_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing
        ExApp.DisplayAlerts = False
        If ExWS IsNot Nothing Then ExWS = Nothing
        If ExWB IsNot Nothing Then ExWB = Nothing
        ExApp.Quit()
    End Sub