Can I delete all my journal entries and start again?
Yes you can, but LiveJournal currently does not provide any means to delete all of your journal entries from your journal with one command. To achieve this, you must delete each post (see: http://www.livejournal.com/support/faqbrowse.bml?faqid=3 ).
This can be done from either the web client ( http://www.livejournal.com/editjournal.bml ) or by using the Windows client. If you have not yet downloaded the client you may do so at http://www.livejournal.com/download/ .