Dark Wood paneling on 2 walls, outdated. How to bleach to lighten?

You can paint it any color you like, Prime the paneling with a stain blocking primer. Paint it on just like a normal wall, masking off the ceiling, trim and baseboards. Cut in the edges with a brush, and roll on the primer using a 3/8-inch roller cover. Allow to dry completely, at least 24 hour - latex paint and primer will work

Try this link it may be helpful homeguides.sfgate.com/bleach-paneling

Make sure its real wood, not paneling. Then you would have to strip the stain out using a paint remover for stain like Klean-Strip, I use steel wool to get it out of the wood pores. Then wipe down. Apply your wood bleach and depending on the amount of stain in the wood pores it may take multiple applications to get to the degree of lightness desired. Its going to be alot of work.

Personally, I would tear it off and put up drywall or paint it.

You can paint it or white wash it: (and I also included a link for bleaching that works:)

https://www.hgtv.com/design/decorating/design-101/painting-wood-paneling

https://domino.com/bleaching-furniture-diy#all

http://justatouchofgray.blogspot.com/2011/08/whitewash-treatment.html

Just paint it.

You could calk the connections then paint with aroma free Kilz primer, then paint as you like. We did this. OR just thin down some paint and white wash it with thin paint like milk paint.

The best thing is to paint them.

Can't bleach paneling. The wood tone/grain is either a photograph or embossed onto a substrate. Removing or painting is the only option.

Make sure the paneling is clean and dry. Prime with a good stain blocking primer like Zinsser 123 or BIN. Then paint like painting regular walls. If the paneling has grooves you can fill them with non shrink drywall patching compound. Just put on enough to fill the grooves. Let it dry overnight. Next day use a damp sponge to smooth the patch. Then prime and paint.