It's been a few months of using your plugin and unfortunately, it is not removing unverified users. I had to delete manually this morning more than 10,000 unverified users.
I believe to have emailed you a few months ago but I do not recall to have received an answer from you.
Thanks in advance.
This is a common issue in WordPress. Somehow, WordPress cron isn't running on your site. You can set a server cron on schedule to fix this issue.
Please follow this article - https://www.hostinger.com/tutorials/how-to-fix-wordpress-missed-schedule
(you can start from here - Set Up a Cron Command)