Pour arrêter une application dont on connait le nom, on peut utiliser le code ci-dessous que l'on aura pris soin de placer dans un module général.

On sauvera ce module avec un nom tel que modKillProcess.

Ensuite, via un clic sur un bouton ou tout autre événement, on appellera la sub par :

KillProcess "nomprogramme.exe"

Dans la partie déclarative d'un module on écrira :

Option Compare Database
Option Explicit

Type PROCESSENTRY32
    dwSize As Long
    cntUsage As Long
    th32ProcessID As Long
    th32DefaultHeapID As Long
    th32ModuleID As Long
    cntThreads As Long
    th32ParentProcessID As Long
    pcPriClassBase As Long
    dwFlags As Long
    szexeFile As String * 260
End Type

Declare Function OpenProcess Lib "kernel32.dll" ( _
                             ByVal dwDesiredAccess As Long, _
                             ByVal blnheritHandle As Long, _
                             ByVal dwAppProcessId As Long) As Long

Declare Function ProcessFirst Lib "kernel32.dll" Alias "Process32First" ( _
                              ByVal hSnapshot As Long, _
                              uProcess As PROCESSENTRY32) As Long

Declare Function ProcessNext Lib "kernel32.dll" Alias "Process32Next" ( _
                             ByVal hSnapshot As Long, _
                             uProcess As PROCESSENTRY32) As Long

Declare Function CreateToolhelpSnapshot Lib "kernel32.dll" Alias "CreateToolhelp32Snapshot" ( _
                                        ByVal lFlags As Long, lProcessID As Long) As Long

Declare Function TerminateProcess Lib "kernel32.dll" ( _
                                  ByVal ApphProcess As Long, _
                                  ByVal uExitCode As Long) As Long

Declare Function CloseHandle Lib "kernel32.dll" ( _
                             ByVal hObject As Long) As Long

Ensuite, la sub... 

Public Sub KillProcess(NameProcess As String)
    Const PROCESS_ALL_ACCESS = 0
    Const PROCESS_TERMINATE = (&H1)
    Const TH32CS_SNAPPROCESS As Long = 2&
    Dim uProcess As PROCESSENTRY32
    Dim RProcessFound As Long
    Dim hSnapshot As Long
    Dim SzExename As String
    Dim ExitCode As Long
    Dim MyProcess As Long
    Dim AppKill As Boolean
    Dim AppCount As Integer
    Dim i As Integer
    Dim WinDirEnv As String

    If NameProcess <> "" Then
        AppCount = 0
        uProcess.dwSize = Len(uProcess)
        hSnapshot = CreateToolhelpSnapshot(TH32CS_SNAPPROCESS, 0&)
        RProcessFound = ProcessFirst(hSnapshot, uProcess)

        Do
            i = InStr(1, uProcess.szexeFile, Chr(0))
            SzExename = LCase$(Left$(uProcess.szexeFile, i - 1))
            WinDirEnv = Environ("Windir") + "\"
            WinDirEnv = LCase$(WinDirEnv)

            If Right$(SzExename, Len(NameProcess)) = LCase$(NameProcess) Then
                AppCount = AppCount + 1
                MyProcess = OpenProcess(PROCESS_TERMINATE, False, uProcess.th32ProcessID)
                AppKill = TerminateProcess(MyProcess, ExitCode)
                Call CloseHandle(MyProcess)
            End If
            RProcessFound = ProcessNext(hSnapshot, uProcess)
        Loop While RProcessFound
        Call CloseHandle(hSnapshot)
    End If
End Sub