JUserPrune Premium Edition for Jooma! 3
For personal, one-man business and non-profit websites only. Limited support.
Current version: 3.1.0. Compatible with PHP 5.3+ and PHP 7, PHP 8.
Updates through the Joomla! update system.
Purchase includes one (1) year free updates.

A plug-in that automatically removes both frontend and backend user accounts that have not been activated or used during a configurable period, or have been idle for too long (also configurable). Customised user groups are not pruned by default but can be included.
Specified user accounts and groups can be excluded from or included in being pruned.

When the plug-in is fired, is configurable, for example only when a registered user logs in or at regular time intervals. In this way the server load can be reduced. Recommended for high volume websites.

Also available as a Business Edition, offering more options and flexibility.

Install or upgrade via Joomla! backend.

Requirements:
- Joomla! 3.5 or later
- PHP 5.3 or later, PHP 7, PHP 8

Basic install, upgrade and setup instructions are in the documentation that comes with the download package.
Configuration overview: see here.

Backend language: English.

License: For personal, one-man business and non-profit use only. License terms are here.
Support: Limited support. Support terms are here. You may find the answer to your question on our forum.

Discount and refund policy: see here.

You may want to try the free standard edition first. The standard edition does not manage backend user accounts.