Algorithus

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.

AWP Disallow Root Control

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

davide.airaghi

This plugin allows any user having at least one of the following capabilities to edit robots.txt: 
– edit_files (standard WP capability) 
– manage_options (standard WP capability) 
– unfiltered_upload (standard WP capability) 
– upload_files (standard WP capability) 
– wpseo_manage_options (Yoast SEO capability) 
– aioseo_general_settings (All In One SEO capability) 
– aioseo_tools_settings (All In One SEO capability) 
– aioseo_feature_manager_settings (All In One SEO capability) 
– aioseo_local_seo_settings (All In One SEO capability)
The “Robots.txt” option is added under “Settings” menu.

AWP Disallow Root Control vs Robots.txt Quick Editor