GunSystem/Assets/Script/Menu/MenuController_2.cs

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

public class MenuController_2 : MonoBehaviour {
    public GameObject[] menuObjs;

    public void closeAllMenu() {
        foreach (GameObject i in menuObjs) {
            i.SetActive(false);
        }
    }

    public void openMenu(int i) {
        closeAllMenu();
        menuObjs[i].SetActive(true);
    }

}