Wait --there is one more important before OP will vanish his account.
-Delete all your posts that can be found on your post history.
It's not necessary to do.
If you have secret and don't want anyone to know, don't publish it on Internet.
A Bitcointalk member only can delete posts but can not delete a thread, opening post of a thread. Even posts if deleted by OP will still be stored by some scrapers.
OP of a topic can not delete his topic or thread, but not in all cases, if the OP made it self-moderated, he will be able to delete the topics. But OP threads are not self-moderated and he can not delete it. But some people can edit the topic to dot or del in a way it would be like the topic is deleted but not the whole thread.