MacBook Pro asking for a 4 digit pin

So I recently bought a MacBook Pro from someone. I toyed around with it before I bought it and everything checked out. After getting it home and beginning the process of connecting it to my iTunes and iCloud and personalizing it, it reset and then prompted me with a 4 digit pin code screen. I don't know this code and neither does the previous owner. After reading up on it I found that it is an "iCloud" security feature and not something the Mac itself has. I have no idea how to get passed this and I've tried every 4 digit pin I think it might be. If it is connected to my iCloud shouldn't I know this? How do I get pass this? Or can I just remove it from my iCloud?