When I bought my Iron it came with this seat on and didn't get the stock solo seat with it. I've just ordered one and can't work out how to get this seat off. 

I pulled out the front horizontal bolt, then undid the upright nut thats right under the butt however the seat won't lift, the thick diagonal bolt is hanging over the seat base and the vertical bolt prevents the base from moving forward to be removed.

 

It looks like I have to take the whole rear wheel off to reach in and undo that bolt, is there something I am missing?