When a calendar event passes it changes status to "previous". In order to view previous events open the administrative side of the calendar and click on the category that you would like to see.
Then use the view options drop down menu (located in the blue bar above your events) to check the previous checkbox located under the display events section.
Once you apply your changes you will see any past events in your events list with a previous stamp next to the item. You can then unpublish the item to remove it from public view.