A web page or an announcement is reference by an URL, and the URL perhaps was shared among users through emails, text messages, other web pages, or even other web sites ...etc; thus by removing an announcement, will cause that reference to be broken. Thus normally, an announcement should not be deleted. New announcements will make the old announcement obsolete, by pushing it down the stack; and removing it completely makes it unnecessary.

With all that said, however if a post or an announcement is needed to be delete, here are the steps:

1. Navigate to the page or announcement to be deleted
2. Click on the "More actions" button, upper right corner
3. Select Delete page, and confirm the action.