How to save the destroyed state of an enemy ?

On Trigger enter the enemy get destroyed but every time I play the game the enemy get back.
How to save the destroyed state of enemy so that the enemy wont get back ?

You would have to save a bool that contains data on whether the enemy was destroyed or not. You could try using PlayerPrefs for this. For example:

const string EnemySaveData = "WasDestroyed";

    private void OnTriggerEnter(Collider other)
    {
        // Enemy was destroyed
        Destroy(other.gameObject);

        // Save this info
        PlayerPrefs.SetString(EnemySaveData, "true");
    }

And when you first hit play, you need to check if the enemy was destroyed last time:

    private void Start()
    {
        string WasDestroyed = PlayerPrefs.GetString(EnemySaveData);

        // Destroys enemy if they were destroyed
        // previously
        if (WasDestroyed == "true")
            Destroy(gameObject);
    }

@mak431020

what do you man as in another enemy spawns ?
as it is impossible for the same enemy that is destroyed to just still be there it would be done in the spawn manager that is spawning the clones of a prefab in the scene and as such is where you would limit the spawning.