First i would take off all mushy parts. I am assuming you mean the main rhizome. If leaves are growing out of smaller side rhizomes you can take the side rhizomes off the main one, wash them thoroughly in a solution of 90/10 % water and bleach. Leave them out to dry in a shady spot. The fresh wound where you cut them from the main rhizome should callous over and look dry before you replant them. If you are going to put them back in the same pots you must scrub the pots and disinfect thoroughly.