Arsen Rabinovich: I would do it slowly, some PBN links are super strong (heard from a friend), and can cause a big drop in rankings if removed. So just like Leighton said, do it slowly and replace as you remove.
Steve Wiideman: I`m just guessing here, but if you pulled PBN links from your holistic SEO strategy, you`re probably heading in the right long-term direction.