Conditonal statements for loading and unloading swfs

i have a bunch of _mc that load .swfs into the same shell2_mc

im trying to figure out how to replace one .swf with another…(swapping) or unloading the previous swf before loading the next swf onClick

possibly using an (if) statement ? …or var swap:boolean = true;
any suggestions

bio_mc.addEventListener(MouseEvent.CLICK, onClick);
function onClick(event:MouseEvent):void
{
var imageRequest:URLRequest = new URLRequest(“bio2.swf”);
var imageLoader:Loader = new Loader();
imageLoader.load(imageRequest);
shell2_mc.addChild(imageLoader);

}