Customer currentCustomer = _db.Customers.First()

public void DeleteOrderLine(int id)
        {
            foreach (Order order in CurrentCustomer.Orders)
            {
                if (order.OrderLines.Any(e => e.Id == id))
                {
                    OrderLine forDeleteOLine = order.OrderLines.FirstOrDefault(e => e.Id == id);
                    CurrentCustomer.Orders.FirstOrDefault(e => e.Id == forDeleteOLine.OrderId).OrderLines.Remove(forDeleteOLine);
                    Db.SaveChanges();
                }
            }
        }

public void CreateOrderLine(OrderLine orderLine)
        {
            if (orderLine != null)
            {
                CurrentCustomer.Orders.FirstOrDefault(e => e.Id == orderLine.OrderId).OrderLines.Add(orderLine);
                Db.SaveChanges();
            }
        }

[HttpPost]
        public ActionResult Login(string login, string password)
        {
            _currentCDetail = new CustomerDetail();
            LoginClass loginObject = new LoginClass();
            Customer customer = loginObject.Login(login, password, _currentCDetail.Db);
            if (customer != null)
            {
                _currentCDetail.CurrentCustomer = customer;
                Session["CurrentCustomer"] = _currentCDetail;
                return RedirectToAction("ListOrders", "Main");
            }
            return View();
        }