defriend

verb

1. (uncommon)To remove from one's list of friends (e.g. on a social networking website).

   “2005, Schmitt et al, Professional CSS: Cascading Style Sheets for Web Design But why subject myself and friends to the awkward social construct of being virtually "defriended" because I want to save some space on a Web page?”

   “Likewise, the actions of friending or defriending someone send out messages of their own.”