Crain’s New York Business: For the past 10 years, a red neon sign towered over Columbus Circle, broadcasting a simple, three-letter message: CNN. The sign was visible from Central Park and all points north. Now, the sign is gone. The cable news network, along with parent Time Warner, is planning to move out of the Time Warner Center at Columbus Circle by 2018 and take space at an office tower being developed at Hudson Yards.