if were me, remove all paper wash the tub with soap. mold propagate by spores, so you must clean the tub and dry it out completely. replace the paper, meanwhile, remove the cuttings, put them in a cup of water (kinda like flowers, while you wash one by one, soak them in a kitchen soap with a little of bleach... shake them dried completely, then wet their bottoms only and if you have a growth hormone, do a small dipping and put them in a whole new bedding, and new cover (moist paper) close the box, but check again in the morning/
if mold is not too bad, you may be able to re do this, changing their bedding washing box, and will be OK. I would check at least a couple of times a day, if you can lose a little bit, it would be good to using a sharp trimmer to take a little bit, where it was cut, mold seems to infiltrate those areas first... cuts at bottom can be about 1/4" from the node. I would not sacrifice a node, you need them. but internodes, you can trim a little, just to get rid of any mold spores that may be there, also, you can use warm water to wash and rinse them.
I had done this, and have also dumped the entire batch.. you may quarantine those with worse mold... so, it won't spread to others, that is after you wash them throughly.
Best luck