Three buttons over from "Welcome Back, Komikaze" at the top left under the EdgeGamers logo, you will find "My Account".
Click that, look at the side bar on the right, find "My Options" and click it.
Scroll down to the second box/section and you will see a drop down menu in the middle of that section.
There are a few options there, including a couple different ways to not be notified of replies.
EDIT: Lock, please.