Ayesh Karunaratne

This plugin ensures that when users of your website (including site administrators), the browsers are instructed to clear all residue such as cookies and caches to enhance the security.
<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Clear-Site-Data" rel="nofollow ugc"><code>Clear-Site-Data</code> HTTP header</a> is sent when a user logs out, which supported browsers will react by removing all existing cookies, cache, and other storage. It will not remove saved passwords, permissions, adblocker rules, and other data that are supposed to be permanent.
This plugin prevents possible security vulnerabilities such as clicking the “Back” button in the browser after logging out revealing the pages that should not have been accessible after logging out. Furthermore, this cleans the browser cache, which prevents accessing authenticated media assets (such as purchased images) from the browser cache of a victim.

Clear Logout

A tiny WordPress plugin to clear all browser data related to the site upon logout (With Clear-Site-Data header).

John Blackbourn

There is no built-in way for your visitors to “log out” of password protected posts once they’ve entered the password. Even logged in users cannot log out of password protected posts by logging out of their account. This plugin solves that problem by providing a link for your visitors to log out of password protected posts.
<h3>Setup</h3>
After installing the plugin, add the following code somewhere in your theme to display a link for logging out of password protected posts:
<pre><code><?php do_action( 'posts_logout_link' ); ?>
</code></pre>

Log Out Password Protected Posts

Provides a template tag for a link for visitors to log out of password protected posts.

Clear Logout vs Log Out Password Protected Posts