I lost my Level 7 account....?

Yahoo does not have to justify what you call censorship. The idea of freedom of speech does not apply on privately-owned websites. Corporations such as Yahoo have the right to make and enforce rules. They also have the right to suspend accounts, without notice, and without having to justify themselves. You GAVE them those rights when you agreed to the terms of service when you signed up here:

15. TERMINATION

You agree that Yahoo! may, under certain circumstances and without prior notice, immediately terminate your Yahoo! account, any associated email address, and access to the Service. Cause for such termination shall include, but not be limited to (link provides list of reasons):

http://info.yahoo.com/legal/us/yahoo/utos/utos-173...

As to understanding what you did 'wrong', the numerous violations were warning shots across your bow, so to speak. That was the YA staff way of alerting you that you were in danger of termination. What the final trigger was may never be known. It might have been one single posting just TOO far over the line -- or just the fact that after numerous warnings, you postings did not moderate sufficiently. Supposedly, the YA staff are legally proscribed from specifically stating exactly what the basis of the suspension was.

You can, of course, try appealing. There have been any number of successful appeals of high-level suspensions -- including the current #1 account on the leaderboard.

"And how does Yahoo justify censorship?"

They don't have to. It's their website. They get to set the rules, just like you set the rules in your own house. And, just like in your house, if someone doesn't like it, they can leave.

I think that you should have got an answer about why it was deleted.

appeal it, or just start over