Un-publish posts

Edit those posts and change their status to ‘Private’ or ‘Draft’.

If you don’t like to retain the posts, you can delete them as well.

That’s not quite the right answer. WordPress stores documents as “published” or “pending review” or “unpublished.” Changing a document to “unpublished” lets you store the page while it’s not available. Tip: DO NOT click the check box for private, as private changes the page status to “published” and those pages can appear on your site in places you wouldn’t expect: like when someone looks at a list of the posts in one of your blog’s categories.

Yes, this does seem inconsistent with the labeling in the WP menus, but the inconsistency is actually in the theme, not WordPress.