Collapsing view window?

If I have the main window open and want to view my project from another angle I can drag those horizontal lines and make a new one…But how do I make it go away when I am done with it??:confused:

http://wiki.blender.org/index.php/Doc:2.6/Manual/Interface/Window_system/Arranging_frames

See demo here http://screencast.com/t/s2sNSbX6K5js

Thank you Thank you!