channeleaton

For large multisite installations of WordPress, it’s easy to let user management go by the wayside. Many times we forget to disable or remove old user accounts, leaving our sites open to users who are no longer part of our organization.
Mass-Disable Users (MDU) aims to fix that.
MDU allows super-administrators to disable old users while retaining all of the author information. This is especially important for news sites.
How does it work?
MDU takes a list of email addresses (in CSV format) and compares it to the existing WordPress users database then any users who do not exist in the CSV file are demoted to Subscriber in every blog!
NOTE: This plugin only works on multisite!

Mass-Disable Users plugin for WordPress

Allows network admins to disable users via CSV while retaining all author information.

Roy Tanck

This plugin will help you:
<ol>
<li>Find plugins and themes that are not active on any blog.</li>
<li>Determine the impact in case a theme/plugin needs to be upgraded, removed or reconfigured.</li>
<li>See if a widget is in use on any blogs, and track down where.</li>
<li>Find users who do not have a role on any site (and are not network administrators).</li>
</ol>
This plugin currently does nothing on single-site WordPress installs.

Network Admin Assistant

Helps you manage a WordPress network by displaying useful statistics.

Mass-Disable Users plugin for WordPress vs Network Admin Assistant