How to destroy a MFC menu?

I have a weird problem regarding to the MFC menu.

I had a Right-Click-Menu from my application, at the same time, my
application received an event which popup a Modal-Dialog. The Modal-
Dialog sits under the Right-Click-Menu and above the application
screen. It freeze my application (not until I hit an ESCAPE command to
destroy the Right-Click-Menu).

In order to have a work around solution, I implement the following
whenever the Modal-Dialog popup.

    CWnd* pWnd = AfxGetApp()->GetMainWnd()->GetActiveWindow();
    if(pWnd)
        pWnd->SendMessage(WM_CHAR, VK_ESCAPE);

I tried this on my machine, and it won't work. But I the same code on
a different machine, it works fine once (the Right-Click-Menu is
gone), but the second time, it won't work again.

I am really frustrated with what to do, can anyone please help?

I also come across the msdn, with the following:

    CWnd* pMain = AfxGetMainWnd();
    if (pMain != NULL)
    {
        CMenu* pMenu = pMain->GetMenu();
        if (pMenu != NULL && pMenu->GetMenuItemCount() > 0)
        {
            for ( int i=0; i<pMenu->GetMenuItemCount(); i++ )
            {
                if ( pMenu->GetSubMenu(i) != NULL ) {
                    pMenu->DeleteMenu(i, MF_BYPOSITION);
                    pMain->DrawMenuBar();
                }
            }
        }
    }

But I tried the code, and it still doesn't work. Can you guys please
guide me a bit?