How can users delete their own account?
There's no way to do that. It would require a custom development.
Are you sure it's a good idea anyway?
Part of our site has a general area for authenticated users, with a forum and some other resources. They can self-register to this. We want to attract people in this way. However, they would also like to be able to unregister themselves.
It seems to me that if self-registering is a possibility; then the possibility to unregister should also exist.