Removing an object

1

I have an array of objects that move across the stage and once they get to x=0 i want to remove them, how can i check to see if they have gotten to x=0.


private function moveToTheLeft(e:Event):void {
            if (x > 0) {
                x -= stepSize;    
            } else {
                removeChild(this);                
            }
        }

as you might have guess the removeChild(this) does not work, once the object reaches x<0 flash freaks out.