ActionScript 3.0 :: Erase A Sprite Completely

I recently saw "Remove or Reuse" by badaboom, in which he set the the invader instance to "null".In my constructor, I have a sprite variable as [code]When the user clicks the start button, the trail sprite is used.[code]After the user click the start button, a timer starts and the trail is drawn [code]Since this is a simulation, the user will want to erase all the trails drawn at some instance to show new examples. In in the reset button, if I set:[cod]Then do I lose the trail variable? Because I need to re-use it later in the start button and in the timer. I also learned somewhere that garbage collection only collect when the variables does not link to any other instances. In this case, the trail is still sticking onto the container_mc right?I have tried container_mc.removeChild(trail) alone, but when I addChild(trail), none of the trails drawn are deleted.