It's not clear during the installation process but you seem to get as default when you install ezwebin_site and ezwebin_site_admin. I also seem to have (in my siteaccess subdirectory) admin, eng and setup. eng and ezwebin_site seem identical, setup is empty, admin I'm not quite sure about.
I've read the section in the manual on siteaccess and I am a little bit less confused but it's not *totally* clear to me yet.
If I want to change the names for siteaccess can I just change the names of the subdirectories in /var/www/htdocs/ezpublish/settings/siteaccess? Can I safely remove the unwanted ones? It would seem to be sensible to have just the default (user) site access and the admin one.
You can rename the siteaccesses if you want just by renaming the directories in settings/siteaccess/, though you will also want to edit the settings in settings/override/site.ini.append.php to match the new names - have a look particularly in the [SiteSettings] and [SiteAccessSettings] parts. You might also need to edit the anonymous user's role in the User Accounts section in the administration interface to allow login access to the new siteaccess names.