Nope, not at all. If an account is deleted, so are all of the posts. That would ruin a ton of threads.
We used to let people delete accounts, but after so many threads were destroyed as a result, we don't do that anymore. In addition, some folks deleted their accounts in a huff and regretted it later. So instead, we deactivate it if somebody really wants that. But honestly, just leave if you don't want to come back. Simple.