Как удалить связь Many-tomany hibernate java

Есть два класса:

package server.dao.entities;
import org.hibernate.annotations.LazyCollection;
import org.hibernate.annotations.LazyCollectionOption;
import javax.persistence.*;
import java.io.Serializable;
import java.sql.Date;
import java.sql.Time;
import java.util.HashSet;
import java.util.Set;
@Entity
@Table(name = "orders")
public class OrderEntity implements Serializable
{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id_order", nullable = false)
    private int idOrder;
    @Column(name = "date", nullable = true)
    private Date date;
    @Column(name = "time", nullable = true)
    private Time time;
    @ManyToOne
    @LazyCollection(LazyCollectionOption.FALSE)
    @JoinColumn(name = "id_customer", referencedColumnName = "id_customer", nullable = false)
    private CustomerEntity customer;
    @ManyToMany
    @LazyCollection(LazyCollectionOption.FALSE)
    @JoinTable(name = "order_item", joinColumns = @JoinColumn(name = "id_order"), inverseJoinColumns = @JoinColumn(name = "id_item"))
    private Set<ItemEntity> items = new HashSet<>(0);
    public OrderEntity(Date date, Time time, CustomerEntity customer, Set<ItemEntity> items)
    {
        this.date = date;
        this.time = time;
        this.customer = customer;
        this.items = items;
    }
    public OrderEntity()
    {
    }
    public Set<ItemEntity> getItems()
    {
        return items;
    }
    public void setItems(Set<ItemEntity> items)
    {
        this.items = items;
    }
    public int getIdOrder()
    {
        return idOrder;
    }
    public void setIdOrder(int idOrder)
    {
        this.idOrder = idOrder;
    }
    public Date getDate()
    {
        return date;
    }
    public void setDate(Date date)
    {
        this.date = date;
    }
    public Time getTime()
    {
        return time;
    }
    public void setTime(Time time)
    {
        this.time = time;
    }
    public CustomerEntity getCustomer()
    {
        return customer;
    }
    public void setCustomer(CustomerEntity customer)
    {
        this.customer = customer;
    }
}

Item:

package server.dao.entities;
import org.hibernate.annotations.LazyCollection;
import org.hibernate.annotations.LazyCollectionOption;
import javax.persistence.*;
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
@Entity
@Table(name = "item")
public class ItemEntity implements Serializable
{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id_item", nullable = false)
    private int idItem;
    @Column(name = "name", nullable = true, length = 45)
    private String name;
    @Column(name = "price", nullable = true)
    private Float price;
    @ManyToMany
    @JoinTable(name = "order_item", joinColumns = @JoinColumn(name = "id_item"), inverseJoinColumns = @JoinColumn(name = "id_order"))
    @LazyCollection(LazyCollectionOption.FALSE)
    private Set<OrderEntity> orders = new HashSet<>(0);
    public ItemEntity(String name, Float price)
    {
        this.name = name;
        this.price = price;
    }
    public ItemEntity()
    {
    }
    public Set<OrderEntity> getOrders()
    {
        return orders;
    }
    public void setOrders(Set<OrderEntity> orders)
    {
        this.orders = orders;
    }
    public int getIdItem()
    {
        return idItem;
    }
    public void setIdItem(int idItem)
    {
        this.idItem = idItem;
    }
    public String getName()
    {
        return name;
    }
    public void setName(String name)
    {
        this.name = name;
    }
    public Float getPrice()
    {
        return price;
    }
    public void setPrice(Float price)
    {
        this.price = price;
    }
}

Нужно удалить только связь в ассоциативной сущности , Пытаюсь удалить так :

    DAO<OrderEntity> DAO = new DAO<>(OrderEntity.class);
    DAO<ItemEntity> itemEntityDAO = new DAO<>(ItemEntity.class);
    OrderEntity orderEntity = DAO.readById(idOrder);
    ItemEntity itemEntity = itemEntityDAO.readById(idItem);
    orderEntity.getItems().remove(itemEntity);
    itemEntity.getOrders().remove(orderEntity);
    itemEntityDAO.update(itemEntity);
    DAO.update(orderEntity);

Но в БД , никаких изменений не происходит