Help with mod.

I made a worm boss and when the player dies the worm doesn't despawn?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Terraria;
using Terraria.ModLoader;
using Terraria.ID;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;


namespace Cerberium.NPCs.Worm
{
[AutoloadBossHead]
public class CelestialWormHead : ModNPC
{
private Player player;
public override void...

Help with mod.