Prepping Blue-stained Post and Beam

[Smith Newnam]

Hi! I'm working on a post and beam house and prepping some of the exposed wood. In the construction phase, the beams unfortunately didn't get the best care and developed a lot of deep mold and blue stains. I've planed and sanded the vertical faces, but discoloration remains.
Any advice on dealing with what I have? I've got some oxalic acid I could try, but I'm wondering what other options there are. I'd like to finish these with tung oil or something similarly "true" to the wood. Not generally a fan of wood stains, since they usually make wood look all the same color and fake, but maybe there's something that could work? Do I just have to deal with the stains? Perhaps pickling or a white-wash is one of my few options to reduce the visible effects of the staining? Looking for any suggestions, really. Thanks!

(photos below, which show the range of the staining. Some are not bad at all, where others are pretty noticeable.)

-Smith
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Imgur link: https://imgur.com/a/Wj5afez

[David Utterback]

My good friend used clorox diluted about 50% to remove stains from oak post and beams. It was applied with a handheld sprayer and the reaction was not immediate. Ensure limited exposure time with lots of ventilation. Good luck!