Pop the clutch shoes out, then take the large nut off using the wheel nut box wrench.
The flywheel is on a taper, so you will have to get a large flat screwdriver behind it and twist.

Don't do what I first did and spend 30 mins rotating it before realising it is not unscrewing!!![&:][&:][&:]

Your Hand Book will show this assembly in and exploded diagram.