Actionscript, disable function

Hello,

I'm following this tutorial. http://www.riacodes.com/flash/falling-snow-christmas-card-with-as3/ to make an interactive christmas card.

I want to make a button to stop the snowing. This is my code:

/*Sneeuw begint hier*/
addEventListener(Event.ENTER_FRAME, createSnow);

function createSnow(event:Event):void {
var snowflake : Snowflake = new Snowflake();
snowflake.x=Math.random()*stage.stageWidth;
snowflake.y=0;
addChild(snowflake);
snowflake.addEventListener(Event.ENTER_FRAME, moveSnowflake);
}

function moveSnowflake(e:Event):void {
if (e.target.y<stage.stageHeight) {
e.target.y+=10+Math.random()*1;
e.target.alpha-=0.015;
e.target.scaleX=e.target.scaleY-=0.01;

} else {
e.target.removeEventListener(Event.ENTER_FRAME,moveSnowflake);
removeChild(e.target as Snowflake);
}
}
/*Einde sneeuw*/


/*Next knop*/
next_btn.addEventListener(MouseEvent.CLICK,Next);
function Next(event:MouseEvent):void {

if (toestand==1) {
initTypewriter(tekst2);
} else if (toestand==2) {
initTypewriter(tekst3);
} else if (toestand==3) {
initTypewriter(tekst4);
} else if (toestand==4) {
initTypewriter(tekst5);
} else if (toestand==5) {
initTypewriter(tekst6);
bg_outdoor_mc.visible=false;
//disable the snow??????????

I'm new to actioscript 3, so please tell me how to stop the snow....