How many of these people do you actually know, like or value in your life? How many of them know? If they do, how many of them actually converse with you from time to time? If they don’t, why do you keep them on your facebook? How many of them never actually respond or say anything when you post? How many of them “like” what you write but ignore it’s meaning and purpose?
Then, why keep them?
Think, act and life will go on even without people who’s life on facebook is limited to Farmville!