How do i take out the cylinder from rear breaks

Now in english

i have problems whit the rear breakes. They where sent to painting, but when i recived the calipers i noticed that
it was dirt inside them, (sand)

Now i need to take of the piston on the rear calipers and cleane the caliper inside.

How do i remove the piston from the caliper?

best regards tomislav

In english please !

http://wiki.seloc.org/a/How_to_Rebuild_a_Brembo_Caliper


HTH’s

thanks