These are sample events. You can delete them by clicking "Edit this page" in the Supporter Nav on the right, or from your Control Panel navigate to [events] > Events & subpages.
You use event pages for each scheduled event or speaker at your conference, and organize them under a calendar page. This allows you to optionally enable attendees to RSVP for each event or speaker, and provide detailed information about each.
Watch this video about setting up a calendar and creating an event.