How can i delete a movieclip thats inside a parent

1

stop();

this.addEventListener(MouseEvent.MOUSE_DOWN, active);
function active (e:MouseEvent):void {
this.gotoAndStop(2);
MovieClip(parent).memb2.gotoAndStop(1);
MovieClip(parent).memb3.gotoAndStop(1);
MovieClip(parent).memb4.gotoAndStop(1);
var mem1:m1 = new m1();
MovieClip(parent).addChild(mem1);
mem1.x = 280;
mem1.y = 140;
}

this is adding mem1 to the parent,

now on the next frame i want to remove that movieclip, how would i go about doing this.
i tried just putting
MovieClip(parent).removeChild(mem1);
but it says accessing undefined property

any help?!