LiveJournal provides several technical solutions to help prevent comment harassment in your journal. The first thing that you should do if a user is leaving unwanted comments is to
ban that user from commenting in your journal. To prevent unwanted anonymous comments, or to prevent LiveJournal users from commenting at you anonymously, you can
disable anonymous commenting in your journal. Alternatively, you can set your journal so that anonymous users can
only post "screened" comments, which means that you'll have to approve those comments before they appear to the public.