Stop the snow

Hello…
I have followed directions on how to make snow fall.

http://www.kirupa.com/developer/mx/snow.htm

I used the oval tool to make a round snow drop. Converted it into a movie and named it “winter”. In the movie clip instance the name is “snow”.
I right ckicked the snow drop and clicked Actions. Entered this:

onClipEvent (load) {
//specifies the size of the movie stage
movieWidth = 300;
movieHeight = 200;

//variables that will modify the falling snow
i = 1+Math.random()*2;
k = -Math.PI+Math.random()*Math.PI;

//giving each snowflake unique characteristics
this._xscale = this._yscale=50+Math.random()*100;
this._alpha = 75+Math.random()*100;
this._x = -10+Math.random()*movieWidth;
this._y = -10+Math.random()*movieHeight;
}
onClipEvent (enterFrame) {
//putting it all together
rad += (k/180)*Math.PI;
this._x -= Math.cos(rad);
this._y += i;
if (this._y>=movieHeight) {
this._y = -5;
}
if ((this._x>=movieWidth) || (this._x<=0)) {
this._x = -10+Math.random()*movieWidth;
this._y = -5;
}
}

ON THE 11th LEVEL OF FRAME 1, I ENTERED THIS A/S:

for (k=0; k<50; k++) {
duplicateMovieClip(this.snow, “snow”+k, k);
}

It’s works fine! But…
I only want it to snow for 75 of the 400 frames I have.

I tried using the removeMovieClip (“winter”); on level 11 frame 75
but it doesn’t work.
What am I doing wrong?