unload external SWF using event dispatch

Hi i am working on a flash website where i have a main movie named as Navigation where i have all the navigation buttons and drop menus. i am using switch case method to load multiples external SWFs. so as user clicks on any of the navigation button...it loads the external SWF

now i have a close_btn in the loaded SWF and i simply want the unload the external SWF when user clicks on the close_btn.

I come to know that i can do this by event dispach but i am not sure what code to put in external swf  so when close_btn is clicked it can access the unloader function in main movie and unload the External SWF.

Could you Please help, Thank you !

this is my code

//--------main swf---------------------

import flash.display.Loader;

import flash.display.Sprite;

import flash.events.*;

import flash.net.URLRequest;

          home_btn.addEventListener(MouseEvent.CLICK,Click_To_Close);

          ourstory_btn.addEventListener(MouseEvent.CLICK, clickHandler);

          facility_btn.addEventListener(MouseEvent.CLICK, clickHandler);

          customers_btn.addEventListener(MouseEvent.CLICK, clickHandler);

          sustainability_btn.addEventListener(MouseEvent.CLICK, clickHandler);

          contactus_btn.addEventListener(MouseEvent.CLICK, clickHandler);

//  Dropdown Menu1 Buttons

          menu1.menu_mc1.organicinitiative_btn.addEventListener(MouseEvent .CLICK, clickHandler);

          menu1.menu_mc1.myhope_btn.addEventListener(MouseEvent.CLICK, clickHandler);

          menu1.menu_mc1.target2015_btn.addEventListener(MouseEvent.CLICK, clickHandler);

//  Dropdown Menu2 Buttons

          menu2.menu_mc2.mens_btn.addEventListener(MouseEvent.CLICK, clickHandler);

          menu2.menu_mc2.womans_btn.addEventListener(MouseEvent.CLICK, clickHandler);

          menu2.menu_mc2.teans_btn.addEventListener(MouseEvent.CLICK, clickHandler);

          menu2.menu_mc2.babies_btn.addEventListener(MouseEvent.CLICK, clickHandler);

var loader:Loader = new Loader();

addChildAt(loader,0);

function clickHandler(e:Event):void{

switch(e.target.name){

    case "ourstory_btn": loader.load(new URLRequest("ourstory.swf")); break;

    case "facility_btn": loader.load(new URLRequest("facility.swf")); break;

          case "customers_btn": loader.load(new URLRequest("customers.swf")); break;

          case "sustainability_btn": loader.load(new URLRequest("sustainability.swf")); break;

          case "contactus_btn": loader.load(new URLRequest("contactus.swf")); break;

          case "organicinitiative_btn": loader.load(new URLRequest("organicinitiative.swf")); break;

          case "myhope_btn": loader.load(new URLRequest("myhope.swf")); break;

          case "target2015_btn": loader.load(new URLRequest("target2015.swf")); break;

          case "mens_btn": loader.load(new URLRequest("mens.swf")); break;

          case "womans_btn": loader.load(new URLRequest("womans.swf")); break;

          case "teans_btn": loader.load(new URLRequest("teens.swf")); break;

          case "babies_btn": loader.load(new URLRequest("babies.swf")); break;

  }

}     

//-----------my unloader function in main swf --------------------

function Click_To_Close(event:MouseEvent):void

{

              if(loader != null) {

     loader.unloadAndStop();

}