Popular SEO plugins like WP SEO by Yoast allow you to add a nofollow tag to specific posts and pages.
If you don’t want to use any plugins check out the second post of this forum thread; it will allow you to achieve the same thing
http://wordpress.org/support/topic/add-noindex-tag-to-pages?replies=7
PS: The code mentioned inside the post will add a nofollow tag for all pages. To target a specific page read more about the is_single() conditional tag.
Andrew Nevins
(@anevins)
WCLDN 2018 Contributor | Volunteer support
Even if you add a nofollow tag that doesn’t mean Google definitely won’t visit your page, or unindex your page, you need to talk to Google’s forums if you have an issue with Google: https://groups.google.com/forum/
