Here you go:
Code:
Private Declare Function GetSystemMenu Lib "User32" (ByVal hWnd As Integer, ByVal bRevert As Integer) As Integer
Private Declare Function RemoveMenu Lib "User32" (ByVal hMenu As Integer, ByVal nPosition As Integer, ByVal wFlags As Integer) As Integer
Const MF_BYPOSITION = &H400
Private Sub Form_Load()
RemoveMenu GetSystemMenu(hWnd, 0), 6, MF_BYPOSITION 'Disable Close
RemoveMenu GetSystemMenu(hWnd, 0), 4, MF_BYPOSITION 'Disable Maximize
RemoveMenu GetSystemMenu(hWnd, 0), 3, MF_BYPOSITION 'Disable Minimize
End Sub