你可以使用API函数FindWindow和PostMessage去寻找指定的窗口，并关闭它。下面的例子教给你怎样找到并关掉一个Caption为“Caluclator”的程序。
Dim winHwnd As Long
Dim RetVal As Long
winHwnd = FindWindow(vbNullString, "Calculator")
Debug.Print winHwnd
If winHwnd <> 0 Then
RetVal = PostMessage(winHwnd, WM_CLOSE, 0&, 0&)
If RetVal = 0 Then
MsgBox "置入消息错误！"
End If
Else
MsgBox "Calculator没有打开！"
End If
＇为了让以上的代码工作，你必须在模块文件中什么以下API函数：
Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Public Const WM_CLOSE = &H10