An Allen key, probably 10mm. Don't attempt to move the ring with 6 holes in it, that's the retainer for the self-extractor bolt which you're going to turn with the Allen key. Once the NDS crank with it's preload wave washer and spacers are off, the rest should just slide out of the bearings from the DS, although you might have to give it a little tap with a soft faced mallet.
Thanks for the reply. The last picture was so poor it didn't really show the inside of the spindle but it looks like this, which made me think another tool may be necessary:
Nah, it's just a double hex like the rotor bolt on Shimano freehubs. On the hubs it's necessary to provide clearance for the axle, on the cranks there's no real need for it.
An Allen key, probably 10mm. Don't attempt to move the ring with 6 holes in it, that's the retainer for the self-extractor bolt which you're going to turn with the Allen key. Once the NDS crank with it's preload wave washer and spacers are off, the rest should just slide out of the bearings from the DS, although you might have to give it a little tap with a soft faced mallet.