I don’t know what it is but I have to stare at it all day 
There’s a label that says the wood has been treated with copper azole wood preservative but I’m not sure what this stain is, how do I clean it off without damaging it?
I don’t know what it is but I have to stare at it all day
There’s a label that says the wood has been treated with copper azole wood preservative but I’m not sure what this stain is, how do I clean it off without damaging it?
It’s not a fungus, but copper-treated wood like this can be poisonous, so sanding it down might not be the best option. You really do not want to breathe in that dust.
I’d reccomend painting over it or just hang some art or a poster over it.