this is a basic tip but someone ask me today so i thoguht i would post it.
for windows, go to "RUN" and type "regedit" (without the "")
now click on "My Computer" icon, then go to EDIT > FIND (or Ctrl+F3)
then type what you want to remove, everytime you delete something press F3 and it will keep looking.
WARNING: MAKE SURE YOU NO WHAT IT IS YOU REMOVING BECUASE IT CAN NEVER COME BACK.... EVER.
i have removed loads of stuff like this..... and you may even find some really old stuff 2, i have GTA1 on there