How can Users delete their account by themeselves?
1 Go to admin
2 Go to (system) settings
3 Go to user info settings
4 There you will find a question: "Allow users to delete own account?" Select "yes" and users will be presented with a "delete profile" button in their profile.
This Q&A was found on XOOPS Web Application System : https://xoops.org/modules/smartfaq/faq.php?faqid=475