how to close one window.

[kirenemook12]

hello everyone.
i am making a program which has multiple windows.
how do I program that when one window pops-up, the other closes?
i am using Microsoft visual studio 2010, in a Win32 application.
i am not using a windows form.

[tkud]

DestroyWindow(int windowID)

[kirenemook12]

that command destroys both windows, only one needs to be destroyed. And its a parent window which needs to be destroyed.