Unscrew the clutch springs with a piece of flat metal.

Lift off the clutch cover and withdraw the clutch operating rod and clutch plates.

Engage a gear and undo the clutch retaining nut. This is likely to be tight; it will undo more easily if you "shock" it loose with light hammer taps onto a socket driver.

If you are lucky, the clutch will be loose on the shaft. If it is stuck fast, you may need to use the special puller.