Whenever you reply to a thread it automatically makes you follow it which leads you to get notifs everytime someone replies.
Here's how you remove it
Scroll down at the bottom where you see the message box and click on Settings
Then uncheck this box
You can also go in Watched Thread on the Forum tab and uncheck everything you don't want to keep up with.
Quote from johnny
You can also to go your General Settings and disable it from automatically watching on your posts.
We will try to fix this to have it off by default.