violinista28313 the ability to delete any user is controlled by the user.delete
permission, which I believe is actually missing from the admin panel. We should probably get this fixed at some point 😅 This means that when using the Flarum UI only, there's indeed only administrators who can perform that task. But the permission can be inserted manually in the database to give the permission to moderators, it just won't be shown in the admin panel.
I believe that permission is not protected against admin destruction, so a moderator with that permission would actually be able to delete all administrators from the website. That's probably one of the reason we never showed that permission in the admin panel.
Allowing the users to delete their own account is not possible with Flarum itself but could be added by a community extension. I know this was being discussed together with the other GDPR related features https://discuss.flarum.org/d/26387-gdpr-extension-needed