Getting an error when deleting a prefab clone from the scene?

Question

C++ / C#

How to fix prefab deletion error? I'm very new to Unity and GameDev, would be very grateful for any hints.
Mistake:

MissingReferenceException: The object of type 'GameObject' has been destroyed but you are still trying to access it.
Your script should either check if it is null or you should not destroy the object.

the code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class ClickHelper : MonoBehaviour {




    
 
public GameObject obj;

    public void OnCLick()
    {
        Instantiate(obj);
        Destroy(obj);
    }

    
}

Answer 1

What are you even trying to achieve with this code?
Is the error displayed on the second click? On what line?