Unfortunately there's no easy way to change it. There's no single database entry to modify (not permanently, anyway).
Whenever a member (A) rates another member (B), the rating is part of the rater's (A) account. Whenever the ratee (B) gets another vote, a script is run that tallies the votes from all of the members, giving the ratee (B) a new rating. While you could adjust the current tally for the ratee, it would be erased the next time someone rates that member. Make sense?
And no, you cannot delete the accounts that skewed the ratings in the hope that it would remove their vote. That will show up in the next product.
The only thing you may be able to do is change the vote of each member that skewed the rating, which would probably be a tricky and tedious process.
