private void Delete(int idTask)
 {
     try
     {
         if (repo.Delete(idTask))
         {
             var taskToDelete = TasksSingleton.Instance.Tasks.Where(t => t.IdTask == idTask).FirstOrDefault();
             TasksSingleton.Instance.Tasks.Remove(taskToDelete);
         }
     }
     catch (Exception ex)
     {
         throw ex;
     }
 }