Standard cleaning method is to damp wipe with a 10% bleach/90% water solution. But into soft plastic, quite doubtful you'll be able to clean deep enough (mold sends 'roots' into sealed wood/etc.). I'd not mess around, but carefully seal them up (minimizing movement of/through air) in a bag and dispose of them immediately.
If really mold, it's nothing to mess with. I'd be much more worried about mold in the rest of the house. If bad enough mold can easily lead to severe health problems for occupants and in severe cases houses have been considered as a total loss by home insurance companies (houses have been demolished for 'just' mold).
