ActionScript 3.0 :: Adding Unload On Main SWF And 12 Other Files

I have a main swf that loads 12 other swf files. The loading works. What I need is closing what just loaded. I created a close button Btn1 on all 12 other loaded files. It looks fine but if you keep clicking in a different names the speed of the main swf slows down each time.

Code for Btn1 in all 12 files :
Btn1.addEventListener(MouseEvent.CLICK, buttonClick1);
function buttonClick1(event:MouseEvent):void{
gotoAndStop(16);
};

I am not sure if I need to add an unload on my main swf or on the 12 other file instead of the gotoAndStop. Here is the url to the project. [URL].