I accidentally added a comment to Up vote before discovering that it should have been aa comment to Flag Bad Post comment. Now I can't delete the comment. Can you do that for me?

The problem seems to have solved itself, but the answer is largely no. There are two ways to reverse a vote/rep:

  1. The voter must do it from their account by navigating to the post and clicking the vote button a second time.
  2. We go into the database, delete the record, and update any statistics manually.

Obviously #2 is to be avoided, so except in outstanding cases, you're the only one who can reverse your votes on a post.