How do i create a menu where the user can insert and delete think he/she add? in eclipse javascript google-appengine

this is my servlet: 
public class Tesina {

private UserService us;
private DatastoreService ds;
public Tesina(){
    us = UserServiceFactory.getUserService();
    ds = DatastoreServiceFactory.getDatastoreService();
}   

public void add(String data, String nome, String desc) {
    
        Entity e = new Entity(nome);
        e.setProperty("nome", nome);
        e.setProperty("data", data);   
        e.setProperty("desc", desc);
        ds.put(e);
        
        
        }


public String list() {
    
        Query q = new Query();
        PreparedQuery pq = ds.prepare(q);
        List<Entity> list = pq.asList(FetchOptions.Builder.withLimit(100));
        StringBuffer sb = new StringBuffer();
        
        for(Entity e: list) {
            sb.append("<table>");
            sb.append("<tr><td style=\"border: 1px solid transparent; padding-top:10px;\" id=\"cena\">");
            sb.append("<p class=\"bg-success\">"+e.getProperty("data")+"</p>");
            sb.append("<h4>"+e.getProperty("nome")+"</h4>"+e.getProperty("desc")+"</td></tr>");
            sb.append("</table>");
        }
        return sb.toString();
    }


}

i dont know how to create a delete method, the user might add and delete item on the list. the user might olso be able to add ad img file.

i create this code for add events on a news page, thet people can visit but only the admin (me) can modify the list of news.

thanks for the help, and sorry for the linguage and the layout, this is my first question on Stack overflow.