I ran into this revisions annoyance in WordPress…It’s no problem to turn off the beast, but rather to clean out the existing revisions from the DB.

Luckily others also get annoyed.  Andrei Neculau cooked up a nice sql query that took care of the leftovers

DELETE a,b,c
  1. FROM wp_posts a
  2. LEFT JOIN wp_term_relationships b ON (a.ID = b.object_id)
  3. LEFT JOIN wp_postmeta c ON (a.ID = c.post_id)
  4. WHERE a.post_type = 'revision'