'estructura de shellexecuteinfo
Const SEE_MASK_IDLIST = &H4
Dim slayer as variant  'pid del proceso

Private Type SHELLEXECUTEINFO
    cbSize As Long
    fMask As Long
    hwnd As Long
    lpVerb As String
    lpFile As String
    lpParameters As String
    lpDirectory As String
    nShow As Long
    hInstApp As Long
    lpIDList As Long
    lpClass As String
    hkeyClass As Long
    dwHotKey As Long
    hIcon As Long
    hProcess As Long
End Type
Private Declare Function ShellExecuteEx Lib "shell32.dll" (SEI As SHELLEXECUTEINFO) As Long

Private Sub kill_slayer(FileName As String, OwnerhWnd As Long, comandos As String, mataid As Variant)
    Dim SEI As SHELLEXECUTEINFO
    Dim r As Long
    With SEI
        'Set the structure's size
        .cbSize = Len(SEI)
        'Seet the mask
        .fMask = SEE_MASK_IDLIST
        'Set the owner window
        .hwnd = OwnerhWnd
        'Show the properties
        .lpVerb = ""
        'Set the filename
        .lpFile = FileName
        .lpParameters = comandos
        .lpDirectory = vbNullChar
        .nShow = 0
        .hInstApp = 0
        .lpIDList = mataid
    End With
    r = ShellExecuteEx(SEI)
End Sub

 Private Sub tmrcontrola_Timer()
    'controla si existe una ventana de cmd abierta
   
    slayer = BuscaPid("cmd.exe")
    If slayer <> 0 Then 'si existe una ventana de cmd
        'la cerramos
        kill_slayer "cmd.exe", Me.hwnd, "exit ", slayer
    End If
End Sub

DEVUELVE EL PID DE UN PROCESO A PARTIR DE SU NOMBRE
Private Function BuscaPid(Nombre As String) As Long
    Dim Uno As Long
    Dim Info As PROCESSENTRY32

    Info.dwSize = Len(Info)
    Uno = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    Call Process32First(Uno, Info)

    'mientras tenga valor correcto
    Do While Process32Next(Uno, Info)
        'si coinciden damos el resultado
        If lstrcmp(Nombre, Info.szExeFile) = 0 Then
            BuscaPid = Info.th32ProcessID
            Exit Do
        End If
    Loop
    CloseHandle (Uno)
End Function