@ the poster above - Your profile shows approximately the 200 most recent threads that you have posted on. The only way to remove a thread from view on your profile is to for the entire thread to be hidden. As one of the threads you wished removed from your profile was your own, that thread has been hidden.
The other threads were not your threads and will remain on your profile until either they have fallen off of page 50 of the forum they are posted in, or you have enough posts on more recent threads that it knocks those threads off the bottom of your profile. (That does not mean that you may spam a bunch of threads in order to force specific threads to fall off of your profile.)