This is great advice for anyone on Twitter, not just traders. I unfollow or de-list people all the time. I still follow new people that I discover or are recommended from those I follow. Your Twitter following list should be ever evolving and as dynamic as your real-life relationships. Some people will be your friends forever. Some people you never talk to again. Either way, it is OK.
The article is a good read: Don’t Fade This Crowd « Derek Hernquist