how can i delete all my answers and questions before yahoo shut down?

That's the first good question asked about the shutdown.  That's a great idea. But there's no way to.

Wont be possible lol

If a question that you answered has a best answer, you can't. If one of your questions has at least one answer then you can't delete that question either. Your only option is to email Yahoo and ask them to delete your account and hope they do it. I'm not sure but I think asking them to delete your account means deleting your entire account which means you can't use that email address anymore. Maybe you should just wait.

You can't delete any questions that have been answered but you can delete your answers...one by one.

You can request your data for download before June 30th. I don't think they have any reason to keep the data after that...

On the 20th of April the site will be read only.

On the 4th of May, the site will be gone forever.

I don't think Yahoo let people delete their accounts. I know this may sound stupid, but I was thinking about getting myself banned from Yahoo. I don't want any ties to them after April 20th.

You don't have to worry about that— the site will delete all content including user-generated content.