How do you unfriend or remove a friend?
To unfriend someone:

  1. Go to that person’s profile.
  2. Hover over Friends  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.
If the person you want to unfriend has deactivated their Facebook account, go to your profile and click Friends, then search for the person’s name.

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.

Source: https://www.facebook.com/help/172936839431357?helpref=uf_permalink