WordPress automatically adds wlwmanifest link to your site header for Windows Live Writer support. This is a link tag with a reference to your site’s wlwmanifest.xml file:

<link rel="wlwmanifest" type="application/wlwmanifest+xml" href="https://wpassist.me/wp-includes/wlwmanifest.xml" />

However, this manifest is not used by most users out there. To remove wlwmanifest link from your site header, add the following code snippet to your functions.php file.

remove_action('wp_head', 'wlwmanifest_link');