How can i get this Delay script to work?

i’m trying to get the death of a gameobject to intervene after it is out of the camera view the destroy function works fine but not the waitforseconds!

using UnityEngine;
using System.Collections;

public class score : MonoBehaviour {

	void OnTriggerEnter(Collider other)
		if (other.gameObject.CompareTag("Player")) {
			Destroy(gameObject, 3f); // destroy after 3 seconds

Script Reference - Destroy

Tutorials - Destroy

Next time, copy-paste the code and format it with the 101/010 button.