Andy Feliciotti

This plugin adds a “Unlisted?” checkbox in the “Publish” box while using the classic editor and Gutenberg. When this is checked the post will be excluded from most areas of your website by filtering pre_get_posts filter. This means posts will be excluded from RSS feeds, blog pages, widgets, category pages, archive pages, and more. Additionally it adds a noindex tag to the unlisted page to prevent Google from indexing the page. This is useful if you want to publish some information on your site and allows others to view it via the link without fully publishing.
Features
<ul>
<li>Simple checkbox to unlist posts when publishing a post</li>
<li>Allows you to hide posts from most areas of your site</li>
<li>Add a noindex tag to pages that are unlisted</li>
</ul>

Unlisted Posts

Allows you to easily exclude posts from feeds, category pages, blog pages and more using one checkbox on posts.

masikonis

Postless hides all links related to Posts functionality both in admin interface. This plugin is designed to be used for static websites or other type of projects that needs no Posts feature so the user interface is more clean.

Postless

Disable blogging feature of WordPress in admin, hide all links related to Posts functionality.

Unlisted Posts vs Postless