Every course shell is created with an Announcements forum that is tied to the Latest news block. When we import a prior course into a new term's course shell, we also bring over any announcement forums that exist in the prior course. Deleting the extra announcement links will not only tidy up your course, it will ensure that the announcements you post appear in the Latest news block. Having announcements linked in the Latest news block greatly increases the chances that learners will see important course messages.
When you first open a new course shell, you'll see one Announcements forum.
After you import content from your prior course, you will likely see at least three Announcements links on your course page. The one you want to keep is the topmost one — delete all others! (Turn editing on, click on the Edit link associated with a link you want to delete and click on Delete. Confirm the deletion.)
If you are uncertain which Announcements link to keep, hover over each link and look to the bottom left margin of your page to check the ID number. The highest number will be the most recent Announcements forum that is linked to Latest news.