Forum accounts can not be deleted. You can, however, blank your profile and delete all your subscriptions -- that'll mean you won't get emails from the forum anymore:
http://www.toytowngermany.com/forum/index.php?act=UserCP&CODE=50
http://www.toytowngermany.com/forum/index.php?act=UserCP&CODE=26
http://www.toytowngermany.com/forum/index.php?act=UserCP&CODE=02
http://www.toytowngermany.com/forum/index.php?autocom=gallery&req=subscribe