Because wood is porous it may be difficult to remove the mold stains from sheathing but you can kill the mold by cleaning the sheathing with bleach and water.
Removing mold from attic roof.
Get rid of mold contaminated surfaces by using a wet vacuum the type you can fill its tank partially with water to.
How to remove mold from your attic step 1.
Bleach is corrosive and nasty to use and it kills only surface mold.
In some cases as with a roof leak issue you may have standing water to contend with in.
The most effective way to remove mold from hard porous materials such as wood rafters and plywood roof decking is to scrub it with detergent and water while wearing a dust mask and rubber gloves.
Combine 1 2 cup chlorine bleach.
Wipe the surface with a damp sponge or rag use clean water or wood cleaner use a high efficiency hepa vacuum cleaner on thoroughly dried surfaces and dispose of the picked up.
Removing mold growth from roof sheathing.
Seal off the area.
Wooden wall studs and similar items must often be sanded to remove all traces of mold since wood is somewhat porous.
The first two are effective though often cost prohibitive.
The mold removal process involves scrubbing hard surfaces with a biocide but porous items like insulation and drywall cannot be cleaned and must be thrown out and replaced.