public void Delete(int id)
        {
            var course = context.Courses.FirstOrDefault(C => C.ID == id);

            context.Courses.Remove(course);
            context.SaveChangesAsync();
        }
        public void Delete(int id)
        {
            var track = context.Tracks.FirstOrDefault(T => T.ID == id);

            context.Tracks.Remove(track);
            context.SaveChangesAsync();
        }