ActionScript 3.0 :: Unload An Attached MovieClip By A Click In The Movie Clip Itself

I have an AS3 project (publishing to FP10) where I load a custom made window from the main movie. The custom made window is saved in the Library and has a close button (called exitinteraction_btn).
 
I manage to load the window from the main movie with the following:

var WinA = new windowa();    addChild(WinA);    var myTween:Tween = new Tween(WinA, "x", Elastic.easeIn, 175, 175, 5, true);    var myTween:Tween = new Tween(WinA, "y", Strong.easeIn, 175, 175, 5, true);
 
This is the code in my custom window (which I cannot manage to close and have it remove itself from the main movie when clicked):
  
exitinteraction_btn.addEventListener(MouseEvent.CLICK, closeI);
function closeI(e:Event):void{   this.unloadAndStop();
}
  
I get the following error:
 
TypeError: Error #1006: unloadAndStop is not a function.    at windowa/heyb()