deface (verb) -
To remove a 'friendship' from facebook due to having either accidentily
adding him/her as a friend or actually adding them and reconsidering later.

examples:
"Yeah, there was this guy in my network who added me.
I thought he looked ok, but his updates were really
cramping my news feed, so I had to deface him."

"I went on a date with a girl I met a week before and
like the day after our date she changed her status
to 'in a relationship.' I defaced her."