Go to My Flyertalk on the top left of your screen.

Choose List Subscriptions on the left hand side of your screen.

Each thread you're subscribed to will display. (If you have multiple folders for your subscriptions, only one folder will display at a time.)

Check the box under notification next to each of the threads you want to remove from your notification.

Then at the bottom of the screen there's a jump box titled Selected Threads:

Choose Delete subscription and click Go