radgh

This simple and lightweight plugin adds a “Hide from search engines” checkbox above the publish box to pages. By 
ticking this box, a meta tag will be placed into the <code><head></code> section of your page specifying that robots should 
not index the page.
By default this only applies to pages. You may extend this functionality to posts or other custom post types with a small bit of code. See the FAQ’s tab for further instructions.

Noindex Pages

Ask search engines not to index individual pages by checking an option in the publish post box.

Patryk

The plugin adds a “noindex” field in the edit window for pages, posts and custom post types (CPT), which, when selected – after saving, adds the “noindex” tag to a given page. The tag blocks the indexing of a given page in search engines, e.g. Google.

PRyC WP: Add noindex tag

The plugin adds a "noindex" field in the edit window for pages, posts and custom post types (CPT), which, when selected - after saving, adds …

Noindex Pages vs PRyC WP: Add noindex tag