How do I destroy the object that was instatiated

Questions & Answers
1

I wanna know how I can destroy the game object that was instantiated

    if (previousRockAmount == 0)
    {
        if (previousRockAmount != rockAmount)
        {
            GameObject obj = Instantiate(rockImage, Vector3.zero, Quaternion.identity, transform);
            obj.GetComponent<RectTransform>().localPosition = GetPosition(itemIdentifier - 1);
            obj.GetComponentInChildren<TextMeshProUGUI>().text = rockAmount.ToString("n0");
            previousRockAmount = rockAmount;
            if (rockAmount == 0)
            {
                Destroy(obj);
            }
        }
    }
2

You don’t save a reference to the obj, so you don’t know what to destroy later. Also you sometimes delete the object the same frame it is created, is this what you want?

private GameObject obj; //declare a reference to obj at class level
//private GameObject rocks[] = new GameObject[3]; //declare a list of max 3 rocks at class level

...
obj = Instantiate()
...

Then when you are done with the object do

Destroy(obj);