-User Cp in the upper left hand corner
-Suscribed threads
-List subscriptions
From the subscriptions list check the box at the right side of the screen corresponding to the thread. Move down the page and there is a drop down menu for the selected threads. Select your option in this case delete subscriptions
Not that it matters cause no one can see the threads you are subscibed to, except moderators and Administrators and unless you anger one or break the rules its unlikely they'll be searching from your profile
Just have fun, don't break the rules and keep tabs on the important useful threads.