In my experience, the profile setting only specifies whether email notification is turned on/off by default every time you post. Turn it off to avoid getting into this mess again, but that won't help you with the threads you are already watching.
Wait until you get an email, follow the link in the email, edit your post and deselect the notify option, then save the post. Do this until you stop getting emails.
There may be a better way, but I don't know it.
-Kev
