smart-bow-infrared/Assets/Game_Hyperspace/Script/CountDown.cs

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

public class CountDown : MonoBehaviour
{
   private void OnEnable()
    {
        Invoke("Down", 1);
    }

    void Down()
    {
        Destroy(gameObject);
    }
}