Why delete this.OnEnterFrame is not working?

programming flash
1

Can someone see in this code why the delete is not working? (I commented out the y movement to test to see if it was stopping when x = 10, but it’s not. What am I doing wrong?

function moveCBS() {
	clearInterval(moveCBSInterval);
	_root.container2.onEnterFrame = function() {
			this._x -=5;
			//this._y -=5;
		if (this._x>10) {
			this._x = 10;
			delete this.onEnterFrame;
		}
		}
}
moveCBSinterval = setInterval(moveCBS, 1000);