[Digital]

start_btn.addEventListener(MouseEvent.MOUSE_DOWN,initMovieClips)
 
 for each (var mc: MovieClip in items)
 {
  removeChild(mc);
 }
 for each (mc in items2)
 {
  removeChild(mc);
 
 
 }
 items.length=0
  items2.length=0
}

Должно работать