Gioxx

The plugin provides the administrator with a convenient maintenance page, called E-mail User Cleaner, which will be navigable through the WordPress administrative interface. 
From the E-mail User Cleaner page you will be able to: 
 – generate and download a CSV file containing a complete list of registered users on the WordPress instance. 
 – Specify one or more e-mail addresses (one address per line), corresponding to registered users on the WordPress instance, to be deleted from the system. 
 – Identify duplicated users (based on criteria that checks first name, last name and e-mail address) and decide to select and delete them, also referring to the last login date to the WordPress installation.

E-mail User Cleaner

Delete users corresponding to the specified email addresses.

Janos Moga

This plugin provides lightweight securtiy enhancements to secure your WordPress website. However, this is not a security plugin––most of securtiy enhancements should be made on server level.
Following security enhancements are available: 
* Setting up security headers. 
* Disabling XML-RPC
The plugin also includes functions to clean code output.
Following cleaning enhancements are available: 
* Removing WordPress default SVGs.

Hardened Clean

Lightweight protection to and cleaning of your Wordpress website.

E-mail User Cleaner vs Hardened Clean