I agree everyone has freedom of speech, but I shouldn't be harassed or intimidated at the local library. Go see the County Attorney in person and explain why you feel they should not be there. They should not be allowed in a place where I would frequent that would make me uncomfortable or unwelcome, if you are shunned mention how awful they are to those who have left, and how it hinders your enjoyment of the library.
They will go away the minute anyone tries to challenge them, so challenge them. Go to the library every day, send your friends on the days you can't be there.