If the effective date of a posting has passed its definitely a good idea to disappear the item. Deleting is an option. However before deleting an item which might be useful again (next year) consider simply unpublishing it instead
That way you have a (mostly) ready made item next time around with even less effort. Who knows, one day we may implement a publishing schedule tool which will make items appear and expire at predefined windows making the whole thing a set and forget process.

To unpublish an item you have created:

1) open the item
2) click edit
3) scroll to the bottom
4)Expand the pushing menu
5) un-check the publish box
6) submit the article

Now how do you find it next year. Now THAT is another story ....