Dugonja

This plugin will enhance security of your WordPress site by disabling password reset function over email of WordPress. 
Use with caution since otherwise if you forgot your user password you will need to reset the password directly in the database with phpmyadmin or similar tool. 
Adittionally this plugin will hide notice which say what is wrong “password” or “username” on WordPress login page.

Disable Password Reset

Enhance security of your blogs by preventing password reset over email function.

shazdeh

The WordPress Database Reset plugin allows you to reset the database back to its default settings without having to delete the site and recreate it.
Useful tool for theme and plugin developers who often have to clean up the mess and start over.

WPMU Database Reset

Clean up a single site in a WP network, by removing all posts, comments, terms and media files. A clean slate for the site.

Disable Password Reset vs WPMU Database Reset