Publish box has a date for publishing

When I am editing a draft (I use CKEdit) an item in the Publish Box has been appearing lately that says things like “Publish on: Sep 20, 2012 @ 10:10 Edit”. (That particular one appeared today on Sep 21, although the draft has not been published.) When I click on “Edit” it gives me an opportunity to change the date but it does not give me the option of eliminating the date altogether. How can I eliminate this message?

The “publish on” message was discussed in this forum about three years ago but no one said anything about how to eliminate it from the screen.

Charles Wells