Make external swf disappear?

I am able to load external swf’s either onto levels or into a container mc. I need for them to take up the entire stage area which means that the main movie’s navigation buttons are unavailable. How do I make a loaded external swf disappear so that the main swf shows again? I’ve tried to unload it, make it invisible, and reduce its alpha to zero but the result is that the content of the external swf disappears leaving the empty stage which obscures the main movie.