How do you get your white tree that turned yellow white again?

Yes, I know. It's plastic, once plastic yellows it cannot be whittened. The only thing you can do at this point is spray paint it white.

Bleach slightly diluted. Spray it on.

bleach as a spray, or spray paint it...

.I would spray paint it.

Kelli is right that unfortunately, many white plastics take on a yellowish colour over time simply due to exposure to sunlight or artificial light. Bleach will not be effective in restoring the whiteness (in the same way that it whitens fabric) because the plastic is non-absorbent or water-proof.

I’d spray paint it. But I’d try a small piece or section of it first if you can, because you want to make sure the spray paint doesn’t stay sticky on the plastic needles of the tree.

Thank you all very much! I'll try that after it gets warmer n sunnier here🤣🤣