Removing cursor effect

i used a tutorial to dynamically attach a movie clip to create a bubble effect that occurs when the mouse is moved. It looks great but as i am not used to attaching movies via AS and not manually i have no idea how to remove this effect when it is not required later in the movie. Any help would be great. Sorry for the repeat thread but i am really struggling with this. here is the actionscript i have used:

var i:Number = 0;


var myListener:Object = new Object();
myListener.onMouseMove = function(){
var t:MovieClip = canvas_mc.attachMovie(“bubble”,“bubble”+i,canvas_m c.getNextHighestDepth());
t._x = _xmouse;
t._y = _ymouse;
t._xscale = t._yscale = (Math.random()*80)+20;