Hola,no mira lo podes ahcer de 2 formas una simple y una bien buena usando api's de windows,te digo primero la facil,seria asi,en el evento QueryUnload del form pone esto asi:
Código:
Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
Cancel = 1
End Sub
y la otra seria asi usa el api DeleteMenu y GetSystemMenu.
Código:
Option Explicit
Private Declare Function DeleteMenu Lib "user32" (ByVal hMenu As Long, ByVal nPosition As Long, ByVal wFlags As Long) As Long
Private Declare Function GetSystemMenu Lib "user32" (ByVal hwnd As Long, ByVal bRevert As Long) As Long
Private Const MF_BYPOSITION = &H400&
Private Sub BotonCerrar(ByVal El_Formulario As Form, ByVal Menu_Cerrar As Boolean, ByVal Redimensionar As Boolean, ByVal Mover As Boolean)
Dim Hwnd_Menu As Long
Hwnd_Menu = GetSystemMenu(El_Formulario.hwnd, False)
If Menu_Cerrar Then
Call DeleteMenu(Hwnd_Menu, 6, MF_BYPOSITION)
End If
End Sub
Private Sub Form_DblClick()
Unload Me
End Sub
Private Sub Form_Load()
Call BotonCerrar(Me, True, True, True)
End Sub
saludos.