This has come up several times and there is no way to keep them from coming up. Usually you get the answer to use the "unnotify" button, but that only affects the topics you clicked "notify" in.
You can also go into your profile and on the list, click on Notifications. This will being up a list of threads you are subscribed to or set to Notify. You can select and or all of them and set to Unnotify and save.
You have lots of options in your profile for notifications and such. I guess the software can't cover ALL of the options folks want.
The one I would really like to make go away is that daggon "What did you buy to feed the beast".... that thread has cost me sooooo much money !!!