How to destroy an instantiated object when I touch it?

Hi, I want to destroy intantiated objects before they reach a given target. This is what ObjectPool.cs contains:

using UnityEngine;

using System.Collections; using UnityEngine.UI;

public class ObjectPool : MonoBehaviour

{

 GameObject[] projectiles = null;

 public int numberOfProjectilesToCreate = 1;

 public AudioSource audio1;



 // Use this for initialization
 void Start ()
 {

     projectiles = new GameObject[numberOfProjectilesToCreate];

     InvokeRepeating ("InstantiateProjectiles", 1f, 0.2f);


 }



 // Update is called once per frame
 void Update () {
     

     ActivateProjectile();
     DestroyByTouch ();

 }



 private void InstantiateProjectiles()
 {
     for (int i = 0; i < numberOfProjectilesToCreate; i++) 
     {
         projectiles [i] = Instantiate (Resources.Load ("Prefabs/Prefab_projectile")) as GameObject;

     }
 }





 private void ActivateProjectile()
 {
     for(int i=0; i<numberOfProjectilesToCreate;i++)
     {
         if (Mathf.Round(projectiles [i].transform.position.y) == 130) 
         {
             projectiles[i].SetActive(false);
         }

             projectiles[i].SetActive(true);
             projectiles[i].GetComponent<projectile>().Activate();


             return;

     }
 }



 private void DestroyByTouch()
 {
     Vector2 touchPos;
     
     for (int j = 0; j < numberOfProjectilesToCreate; j++) {
         for (var i = 0; i < Input.touchCount; ++i) {
             if (Input.GetTouch (i).phase == TouchPhase.Began) {

                 if (Input.GetTouch (i).tapCount > 0) {
                     touchPos = Input.touches[0].position;
                     Debug.Log (Mathf.Round (touchPos.x)+" , "+Mathf.Round (touchPos.y));

                 }
             }

         }
     }




 }

}

And this is what projectile.cs contains:

using UnityEngine; using System.Collections;

public class projectile : MonoBehaviour {

 public float life = 2f;
 private float timeToDie = 0.0f;
 public Vector3 targetPosition = new Vector3(0,-2.5f,0);
 public float speed = 12f;
 public float threshold = 0;




 // Update is called once per frame
 void Update () {

     CountDown ();
     AutoMove ();

 }





 public void Activate()
 {
     timeToDie = Time.time + life;
     transform.position = new Vector3 (Random.Range (-6.00f, 6.00f), 9f, 0);

 }






 private void Deactivate()
 {
     this.gameObject.SetActive(false);
 }


 private void CountDown()
 {
     if(timeToDie<Time.time)
     {
         Deactivate ();
     }
 }


 private void AutoMove()
 {
     Vector3 direction = targetPosition - transform.position;
     if(direction.magnitude > threshold){
         direction.Normalize();
         transform.position = transform.position + direction * speed * Time.deltaTime;
     }else{ 
         // Without this game object jumps around target and never settles
         transform.position = targetPosition;
     }
 }

}