Gsxr600

What's up y'all?So back in July my chain snapped off on the freeway. Just recently, I have had time to work on it. Been watching a youtube video on it BUT my i don't know how to take off the front sprocket nut without my chain on the bike...any recommendations?

Also, it seems that I forgot to put it in neutral and i turned the nut & front sprocket a few times...