You can use detergent and mold remover to remove the traces of moldy and black wood. First clean these mold black spots on the board with detergent, but they will still leave traces. Then bleach the board with mold remover.
The moldy and blackened wood board is mainly because a kind of melanin produced by the mold on the wood board due to metabolism is left on the floor. This kind of mold should be cleaned in time, and this kind of black spot will appear after a long time.
You can use detergent to clean the mold and black spots on the wood board first, which plays the role of sterilization and simple cleaning. Generally, traces will be left after cleaning, so you need to use mold remover again.
Mold remover can also be called bleach. It plays a role in bleaching by using the oxidation of chloric acid. It still has an obvious effect on this mold black spot on the board and will not bleach the original color of the board.