This article will describe some of the reasons an answer, question, or comment might be removed from Yahoo! Answers

Content on Yahoo! Answers may be deleted for several reasons:

• Yahoo! determines that your content is in violation of the Yahoo! Answers Community Guidelines or Terms of Service.
• The community determines that your content is in violation of the Yahoo! Answers Community Guidelines or Terms of Service.
• Your question expired with no answers.
• Your question went to voting and the community decided there were no "Best Answers."
• You deleted the question or answer yourself.
• The best answer to your question was removed by Yahoo! or the community. (When a "Best Answer" is removed, the associated question is automatically removed.)
• When a question is deleted, all associated answers, including the "Best Answer", are deleted as well.

Yahoo! reserves the right to remove content that we determine to be inappropriate and/or in violation of the Yahoo! Answers Community Guidelines or Terms of Service.
 

If your content is deleted in this way, you will receive a notification via email telling you that the Yahoo! Answers Community has deleted your content. The email will also contain a link to appeal the deletion. All appeals will be reviewed by  Yahoo! Answers Customer Care and you will receive a notification of the outcome of your appeal, positive or negative, via email.

You may find these articles helpful as well:

• How does Community Moderation work?
• Question or answers reported by the Yahoo! Answers community