Deleting accounts? CL seems not to have heard about it. Besides, in the PP they name the retention of all kinds of data. Anyway, try and request deletion here: http://sfbay.craigslist.org/feedback – you may want to delete your contributions first and/or anonymise your data. Noticing the retention, that is what you may want to try – depending on how much you value the contributions regarding privacy.
URLS:
http://www.craigslist.org