primefaces delete data

[staffmbm]

I'm trying to make delete row function in primefaces datatable. I'm using this method:

package logon;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import javax.annotation.PostConstruct;
import javax.enterprise.context.SessionScoped;
import javax.faces.bean.ViewScoped;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceUnit;
import javax.persistence.Query;


@ViewScoped
@SessionScoped
@javax.faces.bean.ManagedBean(name = "logonTest")
public class LogonTest implements Serializable{
     @PersistenceUnit(unitName="Webbeans_RESOURCE_LOCAL")
     private EntityManagerFactory emf;
    public List<User> getUserList() {
        return userList;
    }

    public void setUserList(List<User> userList) {
        this.userList = userList;
    }

    public List<User> userList = new ArrayList();


    @PostConstruct
    public void init(){
         EntityManager em = emf.createEntityManager();
         // Read the existing entries and write to console
         Query q = em.createQuery("SELECT u FROM User u");
         userList = q.getResultList();
         System.out.println("Size: " + userList.size());
    }

    public LogonTest() {

    }
       public String deleteAction(User user) {
            EntityManager em = emf.createEntityManager();
            em.remove(em.getReference(User.class, user.getId())); 
            userList.remove(user);
            return null;
        }

}

index.xhtml

         <h:commandLink value="Delete" action="#{logonTest.deleteAction(u)}" />

Row is deleted in primefaces datatable, but not in database. After restarting project deleted row is showing up. Can someone help?