If you mean the list that is listed as "friends" you have to go into your friends list and select "Settings" then, tap on "Delete Friend Card" and choose the card that you want to delete.
If you mean the "Acquaintances" list, to delete them you have to tap on the peron that you want to delete and then tap the button in the bottom left hand corner. It should ask "Remove [person's name] from your Acquaintances?" Press yes to remove them.
Hope this helps!