Help, how do I remove the piston from the rear brake caliper on FN2.

Hi guys,
can any one tell me how to remove the piston from a rear brake caliper on an fn2. I have looked at google, youtube and all of the forums and there is plenty of info for front calipers, but I cant find anything that go's into detail. I'm going up to the N/East of Scotland in a couple of weeks, and i need to service the n/s rear brake caliper a.s.a.p,I've got a basic idea but need to be sure, so, any help would be very grateful. Cheers guys.

Just wind it out mate, anticlockwise ,

I've never understood why you have to unwind the calipers, as there is no thread on the piston, but I'm sure I'll find out. Cheers bud.