I want to destroy a windows

There is a way?

In the document you speak about an “unload” function but it doesn’t exists.

Please!

2.6 version supports unload() method:
dhxWins = new dhtmlXWindows();

dhxWins.unload();

mainWindow = new dhtmlXWindows();
windows = mainWindow.createWindow(name, posX, posY, 640, 480);
[..]
windows.unload() <--- FAIL!

I’ve dhtmlxSuite 2010 Rel.1 (DHTMLX 2.6)
The windows class have only “close” method, not unload.

unload is the method of dhtmlXWindows instance.
So, you need to call mainWindow.unload()