The following Generic Handler (C#) is used to unpublish the past/old Events automatically after it's expiration date in Umbraco.

Source Code:

1. using System;
2. using System.Collections.Generic;
3. using System.Linq;
4. using System.Web;
5. using System.Configuration;
6. using umbraco.MacroEngines;
7. using umbraco.cms.businesslogic.web;
8. namespace KPMGAudit.Web.GenericHandlers
9. {
10.     /// <summary>
11.     /// Summary description for UnpublishExpiredEvents
12.     /// </summary>
13.     public class UnpublishExpiredEvents : IHttpHandler
14.     {
15.         public void ProcessRequest(HttpContext context)
16.         {
17.             int EventsNodeId = Convert.ToInt32(ConfigurationManager.AppSettings["EventsNodeId"]);
18.             string strEventStartDate = string.Empty, strEventEndDate = string.Empty;
19.             context.Response.ContentType = "text/plain";
20.             dynamic EventsNode = new DynamicNode().NodeById(EventsNodeId);
21.             List<DynamicNode> eList = EventsNode.Children.Items;
22.             foreach (var Event in eList)
23.             {
24.                 int CurrentEventNodeId = Convert.ToInt32(Event.Id);
25.                 try
26.                 {
27.                     DateTime EventStartDate = Convert.ToDateTime(Event.GetProperty("eventStartDate").Value);
28.                     strEventStartDate = EventStartDate.ToString("MM/dd/yyyy");
29.                 }
30.                 catch { strEventStartDate = string.Empty; }
31.                 try
32.                 {
33.                     DateTime EventEndDate = Convert.ToDateTime(Event.GetProperty("eventEndDate").Value);
34.                     strEventEndDate = EventEndDate.ToString("MM/dd/yyyy");
35.                 }
36.                 catch { strEventEndDate = string.Empty; }
37.                 Document CurrentEventNode = new Document(CurrentEventNodeId);
38.                 if (!string.IsNullOrEmpty(strEventEndDate))
39.                 {
40.                     if (Convert.ToDateTime(strEventEndDate) < DateTime.Now)
41.                     {
42.                         CurrentEventNode.UnPublish();
43.                     }
44.                 }
45.                 else
46.                 {
47.                     if (Convert.ToDateTime(strEventStartDate) < DateTime.Now)
48.                     {
49.                         CurrentEventNode.UnPublish();
50.                     }
51.                 }
52.             }
53.         }
54.         public bool IsReusable
55.         {
56.             get
57.             {
58.                 return false;
59.             }
60.         }
61.     }
62. }

Or

1. public void UnpublishNode(Document CurrentContentNode, DateTime ContentExpiryDate)
2.         {
3.             if (ContentExpiryDate != DateTime.MinValue)
4.             {
5.                 if (Convert.ToDateTime(ContentExpiryDate) < DateTime.Now)
6.                 {
7.                     CurrentContentNode.UnPublish();
8.                 }
9.             }
10.         }