Karan Makani

Admin Robots.txt Editor automatically creates a default <code>robots.txt</code> file (if missing) and provides a user-friendly interface to edit it from the WordPress dashboard.
<h3>Features:</h3>
<ul>
<li>Automatically generates <code>robots.txt</code> with default SEO-friendly rules</li>
<li>Simple admin panel to view and edit contents</li>
<li>Option to reset to default content</li>
<li>Fully editable using a WordPress textarea field</li>
<li>No need for FTP or file access</li>
<li>Uses the official <code>robots_txt</code> hook (recommended by WordPress.org)</li>
</ul>

Admin Robots.txt Editor

Easily create, edit, and manage your site's robots.txt file directly from the WordPress admin panel.

Marat Nepomnyashy

Overview:
At the time of this writing, the latest version of WordPress, version 4.7, 
 has functionality to discourage search engines from indexing the whole site, 
 but not functionality to discourage search engines from indexing only certain 
 specific pages and posts of the site.
Robots Meta Whiz is a WordPress plugin that allows site administrators to 
 deploy custom meta robots tags to discourage search engines from indexing, 
 following links from, caching, indexing images from, and / or have 
 additional custom restrictions on only for certain specifically-designated 
 pages and posts.
It is an easy way to discourage search engines from indexing only specific 
 pages / posts.
This only applies to search engine robots, and will not effect the site’s 
 local search functionality.
Technical summary:
Plugin works by hooking-in special logic into the action ‘wp_head’ to inject 
 the tag <code><meta name='robots' content='...'></code> with restriction directives for 
 the specified pages and posts.
Official project URLs:
https://wordpress.org/plugins/robotswhiz 
 https://github.com/maratbn/RobotsWhiz

Robots Meta Whiz

Easy way to discourage search engines from indexing only specific pages / posts with custom meta tags.

Admin Robots.txt Editor vs Robots Meta Whiz