no site http://www.vbmania.com.br/pages/index.php?varModulo=Forum&varMethod=abrir&varID=381109 consegui o que queria
Sub KillApp(appName As String)
Dim Comando As String
Comando = "TASKKILL -F -IM " & appName
Shell Comando
End Sub
Private Sub Command2_Click()
KillApp "encerrar.exe"
End Sub