This function destroys the specified window. The function sends a WM_DESTROY message to the window to deactivate it and removes the keyboard focus from it. The function also destroys the window's menu, destroys timers, removes clipboard ownership, and breaks the clipboard viewer chain (if the window is at the top of the viewer chain).
If the specified window is a parent or owner window, DestroyWindow automatically destroys the associated child or owned windows when it destroys the parent or owner window. The function first destroys child or owned windows, and then it destroys the parent or owner window.
DestroyWindow also destroys modeless dialog boxes created by the CreateDialog function.
Nonzero indicates success. Zero indicates failure. To get extended error information, call GetLastError.