Helen, thanks for your comments.
I too have had numerous bogus users register on my Moodle. They cannot get into any course because all of my courses require a "key." I do use self-registration, and really don't want to be turning this on and off. I really want to keep this enabled.
In Moodle, I can tell Moodle to delete any user not confirmed within (I use) three days. Works great! However, some of these spamming systems seem to be able to that the URL from the email that they (the spammer) receives, and complete the registration. They end here because they do not have any enrolment key.
I would love to have a similar option in User Accounts|Bulk actions to delete users who are not in any course. As far as I can see, I cannot do this.
My question for you is, does any of this make sense? Do you think it makes sense for me to add a "Feature Request" to add the ability to delete users not in any course?
I know that I should be able to accomplish this if I knew SQL a little better. I am still learning. But for those unwilling to learn SQL and dabble in the database, this feature (i.e., bulk delete users not in any course) would be nice.
If you know anyone who is quick with SQL, maybe you can post the command for this.