[Koha] uninstalling

I installed Koha some time ago but gave up. I now want to try again. I tried updating to v2.0.0 but the updater program threw up error messages. That doesn't worry me since I have no data stored in the existing version. But now if I try to run installer.pl perhaps unsurprisingly I get a message about Koha already being installed. So how do I uninstall Koha so that I can start again. ie what files/directories do I need to delete? And do I need to delete the existing files etc from Mysql? Roger -- Roger Horne, 11 New Square, Lincoln's Inn, London WC2A 3QB http://hrothgar.co.uk/