There are two bolts on the front of the hump that the back seat sits on, remove these then the horizontal cushion of the seat.
Then there are 2 bolts on the bottom corners of the vertical cushion, and possibly 2 behind the fold-down armrest. Then pull the whole cushion upwards and it should come free.
I can't tell you exactly what to do with the parcel shelf because I haven't ever pulled it out of a U13, but it should just be a matter of unbolting the child restraint hooks and pulling out any plastic plugs and then you should be able to lift the corners of the shelf up enough to get at the bolts.