If you are repacking the cylinder there is no need to try to remove the piston on the bottom just pry off the packing and remove the wear ring replace in the same way. you will never get that off the rod and there is no need. Hope L was of help.

Look for a hole or small slot where packing is
There is usually a locking wire that you pop up and out a little then turn the end clockwise that works the locking wire out when reinstalling there will be an L shape in end of wire that locks into shaft then turn opposite direction to install locking wire sometimes it is hard to find