This plugin is similar to deleting users with the bulk operation. There are 2 main differences to the bulk operation. One is the search by multiple keywords(emails only in this case). When you have a list of 100 mails and want to delete the users it is much more comfortable with this plugin. The second difference is the confirmation page. Instead of a comma separated list of the users we have a table with more information about each user in this plugin.
NOTE: In Github we use an empty master branch. The different plugin versions can be found in special branches for each Moodle version.