///<summary>
    ///Delete course in database
    ///</summary>
    public async void DeleteCourse()
    {
        loader.SetActive(true);
        Debug.Log("DELETE name: " + courseKey);
        DatabaseQAHandler.DeleteCourse(courseKey, () => { });
        DatabaseQAHandler.GetCourseLvlQns(courseLvlQns =>
        {
            foreach (var courseLvlQn in courseLvlQns)
            {
                //Debug.Log($"{course.Key} {course.Value.userName}");
                if (courseLvlQn.Value.courseName == courseKey) //Find course created by you
                {
                    DatabaseQAHandler.DeleteCourseLvlQn(courseLvlQn.Key, () => { });
                }
            }
        });
        Stopwatch sw    = Stopwatch.StartNew();
        var       delay = Task.Delay(1000).ContinueWith(_ =>
        {
            sw.Stop();
            return(sw.ElapsedMilliseconds);
        });
        await delay;
        int   sec = (int)delay.Result;

        Debug.Log("Delete elapsed milliseconds: {0}" + sec);
        await Read();

        loader.SetActive(false);
        messageBox.SetActive(true);
        messageBox.transform.GetChild(1).GetComponent <Text>().text = courseKey + " deleted successfully.";
        courseKey = null;
    }
    ///<summary>
    ///Delete course in database
    ///</summary>
    public async void DeleteCourseLvl()
    {
        loader.SetActive(true);
        Debug.Log("DELETE name: " + key);
        DatabaseQAHandler.DeleteCourseLvlQn(key, () => { });
        Stopwatch sw    = Stopwatch.StartNew();
        var       delay = Task.Delay(1000).ContinueWith(_ =>
        {
            sw.Stop();
            return(sw.ElapsedMilliseconds);
        });
        await delay;
        int   sec = (int)delay.Result;

        Debug.Log("Delete elapsed milliseconds: {0}" + sec);
        await Read();

        loader.SetActive(false);
        messageBox.SetActive(true);
        messageBox.transform.GetChild(1).GetComponent <Text>().text = "Deleted successfully.";
        key = null;
    }