Algorithus

<p>This plugin allows you to easily control whether search engines are disallowed from accessing the root directory of your WordPress site by modifying the robots.txt file. You can enable or disable this functionality from the “Reading” settings page.</p>


AWP Disallow Root Control

Disallow access to the root directory via robots.txt with an option to enable or disable.

Processby

<p>The plugin allows you to create and edit the robots.txt file on your site.</p>
<h4>Features</h4>
<ul>
<li>Works with multisite network on Subdomains;</li>
<li>An example of the correct file for WordPress;</li>
<li>Works out of the box;</li>
<li>Totally Free.</li>
</ul>


Robots.txt Editor

Lightweight and perfect for multisite installations.

But in documentation need to say where the option/editor is installed (Settings > Read options).

AWP Disallow Root Control vs Robots.txt Editor