unfriend on facebook
To unfriend someone:
  1. Go to that person’s profile
  2. Hover over Friends down arrow at the top of their profile
  3. Select Unfriend
The person you unfriended won’t be notified.
If you don’t want someone to see your profile, add you as a friend or send you a message, you can block them.
Note: If you unfriend someone, you’ll be removed from that person’s friends list as well. If you want to be friends with this person again, you’ll need to add them as a friend again.