I have problem destroying my objects

I'm building a game where red jewels(cloned) are falling from above and when they collide in game, i'm calling OnCollisionStay2D method to change the tag name of that objects from "crveni" to "gubavci". And then i call the specific method to destroy all the objects with that tag name in Update() event.

My problem here is when i run the game and they collide and when i click to objects they destroy after some time or i must click on rare point on one jewel in order to destroy the objects with "gubavci" tag name.

Here is my entire script which is attach to red jewel game object. PLEASE HELP!!!

 using UnityEngine;
 using System.Collections;
 using System.Diagnostics;
 
 public class crveniScript : MonoBehaviour {
 
     protected Stopwatch timer = new Stopwatch();
     public int Sekunde = 1;
     Vector3 startPosition;
     GameObject crveniDijamant;
     Vector2 mousePosition;
     bool delete = false;
     bool clicked = false;
 
     // Use this for initialization
     void Start () {
         timer.Start ();
         startPosition =  new Vector3(0.1512039f,12.7372004f,0f);
         crveniDijamant = GameObject.Find ("crveni");
 
     }
     void Update()
     {
         mousePosition = Camera.main.ScreenToWorldPoint (Input.mousePosition);
 
         if (Input.GetMouseButtonDown (0)) 
         {
             clicked = true;
             UnityEngine.Debug.Log(Input.mousePosition.x.ToString());
 
         }
         if(delete)
         {
             DestroyAllObject("gubavci");
             //    Destroy(gameObject);
             delete = false;
         }    
     }
     // Update is called once per frame
     void FixedUpdate () {
         
 
         if (timer.Elapsed.Seconds == Sekunde) 
         {
             GameObject go = Instantiate(crveniDijamant, startPosition, Quaternion.identity) as GameObject;
 
             timer.Reset();
         }
 
     }
     void OnCollisionStay2D(Collision2D col)
     {
 
 
         if(col.gameObject.tag == "crveni")
         {
             col.gameObject.tag = "gubavci";
 
             if(clicked)
             {
                 clicked = false;
                 if (collider2D.OverlapPoint(mousePosition)) 
                 {
                     delete = true;
 
                 }
 
 
                     
             }
         }
     }
 
     int counter = 0;
     void DestroyAllObject(string tag)
     {
         GameObject[] ObjectsToDestroy = GameObject.FindGameObjectsWithTag(tag);
         
         foreach(GameObject DestroyObject in ObjectsToDestroy)
         {
             DestroyImmediate(DestroyObject);
 
             counter++;
             UnityEngine.Debug.Log("Upravo unistio" + counter.ToString() + "objekata");
 
         }
     }
 }