No. You have to send a mail to privacy@quora.com and they might take mercy on your asocial soul and delete your account for good (no guarantees though).

No, it's true.

http://www.quora.com/Quora-product/How-do-I-delete-my-Quora-...

I don't know what "deactivating" does, but the account is reactivated if you log in. I tried it and it didn't appear to do anything except log me out. I also sent an email to privacy@quora.com to have the account deleted, but it hasn't happened yet...