Events not getting deleted after expiration date

I am using D6.1.6. I’ve been adding some events to my Calendar Events, however, some events expired last week, but they are still appearing on the Block event on the front page. I don’t want to go thru the process to delete them every time they are expired, they should get deleted or disabled automatically after the expiration date.  You can see it at:  MarocNetwork.com

Any idea? I’d appreciate any input.. Thank you.