I reported an answer, it has five dislikes, and I reported it few times. Why is still there?!?

Because not enough people with a high enough credibility rating have flagged it.

It has to be Reported by a Trusted Reporter in Order for it to be Taken Down

Does not Matter how many Dislikes it has

The Answer also has to be a Violation of the Yahoo Answers Community Guidelines If it does not Break any Rule it may not be Reported and it may not get Taken down

Yahoo is Community Moderated the Staff does not Moderate the Boards

Thanks for admitting to abusing multiple accounts to report someones post.

Because  "thumbs downs"  are NOT reports.   You have to actually REPORT the comment and sometimes things reported numerous times,  still don't get taken down. 

Maybe it takes 5 reports......not 4............maybe it takes 6.........not 5..........

no one knows. 

Troll just use multiple socks, over and over and over again, until it disappears. 

Because thumbs-downs don't mean the post was reported by that # of users. You reported it but you can't know how many others also reported it (maybe some, maybe none). Not enough users have reported it yet, for it to be removed (and there is no standard # of reports that it takes to get a post removed...it varies). If every post that was reported by 1 user was removed, there would be very little on the site at all (the abuse of that would have made the site unusable many years ago). 

You can only report something one time, not "several times."  The number of thumbs down would make no difference.

No-one else bothered to report it.