I have done these twice already on my short career with the bike :)
Remove the piston in the slave by blowing it out with compressed air or your mouth - the choice is yours :) Watch out for the small spring and the ball.
Why twice you may asků I somehow managed to pinch the silicon o-ring I have used from the CS-seal kit I have spare.
I don't know why and how but I have pulled it out again and it was pinched and destroyed. Removed, cleaned and installed real black o-ring I have buyed in the small shop aka 'everything from rubber' nearest to my place. It was maybe 1$ investition.
So get the right o-ring don't be skimpy ;)
I learned the thing by loosing all of the pressure in the clutch overnight. I have a funny feeling that the bleeding is not quite easy in the clutch. I have bled it from the bottom and it was endless repetition of pumping these small bubles out of the reservoir.
Don't loose Your faith ;) it will finally get hard
the clutch I mean.