You are looking at a command called setfriend

setfriend {player} to {option}

Options:
friend - allows them to goto you even if you are set for privacy

enemy - gives you a special warning when they login

kos - kill on sight, you will automatically attack them if they arrive near you. also gives you a warning when they login.

clear - clear just that player's friend setting

setfriend clear

Related:
read the material called friend

read the command called setprivate

read the material called privateThis clears the whole friend list.
Code