How to remove rear tire on Kona Unit X

This feels like a silly question, but I can't for the life of me figure out how to get the rear tire off of my Kona Unit X bike. I got a flat yesterday, and I'm trying to take off the tire to replace it.

I have a bike rack on the back, which goes over the ends of the rear axle. I was able to get the bike rack off, but I can't figure out how to pull the axle and get the tire off.

How do I actually remove the tire?

This is what the rear wheel looks like with the bike rack on the back.

Same side, viewed from above

After I took off the bike rack, and removed this screw (which was very hard to remove), I noticed this cracked green stuff and I'm wondering if this is like some sort of loctite that I wasn't supposed to actually remove ...

Now with that piece removed, it looks like this, but I can't figure out how to actually get the axle out.

Any ideas what to do?

Thanks!