[Vertax]

Развивая мысль, может так:

Object.prototype.del=function(LVL)
{
	if (LVL == undefined) LVL = _root;
	for (var i in LVL)
	{
		if (LVL[i] == this){delete LVL[i]; return true;}
		else if (typeof(LVL[i]) != "function" && this.del(LVL[i])){return true;}
	}
	return false;
}

mc = _root.createEmptyMovieClip("aaa", 1);
mc.zz = {};
mc.zz.prop="qwerty";
trace(mc.zz+" "+mc.zz.prop);

mc.zz.del();
trace(mc.zz+" "+mc.zz.prop);