How do I remove a rust stain from a wooden deck?

sanding the wood will help. You can rent a floor sander to refinish the whole deck.

Try pressure washing but looks like boards need replaced

You can try scrubbing it with a good stiff brush and some warm soapy water. Rinse well, repeat if necessary.

I have to agree with the others, Tia. The depth of the corrosion is concerning. Try washing with a scrub brush and water as Gk suggested to see what you've got. Sanding will get off a lot of what's left. But, if the wood is pitted too deeply you're going to have to make some decisions. If the rust goes really deep, new boards are in order. If it's only really surface pitting, then stain and seal what's there once it's cleaned up. You will probably notice a difference, but the decking will be okay for now. You can always cover the spot with an outdoor rug or piece of furniture - or a new potted plant with a plastic drain dish!

The whole thing needs to be power washed....then restained...

Hi I had a small one but not that deep. . I poured straight Clorox bleach and let sit for a while then washed off . The sun and bleach helped to lighten it up. .good luck .

Naval jelly should do it. The boards look fine to me and I've built loads of decks over the years as a contractor. Naval Jelly is made for rust and it will take the color out of it. You can get it at the auto parts store or True Value might have it.