Admin Robots.txt Editor Plugin — WordPress.com

Admin Robots.txt Editor automatically creates a default robots.txt file (if missing) and provides a user-friendly interface to edit it from the WordPress dashboard.

Features:

Automatically generates robots.txt with default SEO-friendly rules
Simple admin panel to view and edit contents
Option to reset to default content
Fully editable using a WordPress textarea field
No need for FTP or file access
Uses the official robots_txt hook (recommended by WordPress.org)