Configure > Event Settings > Main Details

This is where you can review and change any of the basic details of your event - the name, the location, the principal administrator's email.

This is also where you close the event - when it is over and you no longer wish to take new registrations.  When you click Yes to Registration Closed - anybody clicking on a link to the registration form will see "Registration for this event is  closed" and whatever messages you wish to add in the Messages area.