Ariana

<p>This is a very simple plugin that adds a “robots” meta tag to the head of your site with “noindex” in it.</p>
<p>The effect of the noindex robots meta tag is that search engines will not index your pages and posts at all.<br />
This is a better solution then the wordpress default settings option, which tells search engines to not crawl the URLs in the robots.txt. Because Google (and other search engines) sometimes still index URLs they haven’t crawled, for which they determine relevancy based on anchor text of links which lead to the specific URL.</p>


Simple Noindex

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).

Simple Noindex vs Robots.txt Editor