how to make the timer stop and can automatically proceed to the next scene

Image timerBar; public float maxTime = 5f; float timeLeft;

 // Use this for initialization
 void Start () {
     timerBar = GetComponent<Image>();
     timeLeft = maxTime;

 }
 
 // Update is called once per frame
 void Update () {
     if (timeLeft > 0)
     {
         timeLeft -= Time.deltaTime;
         timerBar.fillAmount = timeLeft / maxTime;
     }
     else
     {
         SceneManager.LoadScene("GameOverDD");
         Time.timeScale = 0;
     }
 }
 public float delay = 1;
 
     [SerializeField]
     private GameObject PanelBenar;
 
     [SerializeField]
     private GameObject PanelSalah;
 
     void Start()
     {
         PanelBenar.SetActive(false);
         PanelSalah.SetActive(false);
     }
 
     void Update()
     {
 
         if (Slot10.cek)
         {
             GameObject objek1 = GameObject.FindGameObjectWithTag("Benar1");
             GameObject objek2 = GameObject.FindGameObjectWithTag("Benar2");
 
             if (objek1.transform.parent.tag == "Jawab1")
             {
                 PanelBenar.SetActive(true);
                 Time.timeScale = 0;
                 StartCoroutine(LoadLevelAfterDelay21(delay));
             }
             else
             {
                 Time.timeScale = 0;
                 PanelSalah.SetActive(true);
                 StartCoroutine(LoadLevelAfterDelay20(delay));
             }
             
         }
     }
 
     IEnumerator LoadLevelAfterDelay21(float delay)
     {
         yield return new WaitForSeconds(delay);
         SceneManager.LoadScene("DragDrop21");
     }
 
     IEnumerator LoadLevelAfterDelay20(float delay)
     {
         yield return new WaitForSeconds(delay);
         SceneManager.LoadScene("DragDrop20");
     }