How to clean oxidation black patch on pvc vinle door frame?

A picture would help. Don't know what you mean by black patch.

here is more info for you

https://washh.com/power-washing/clean-oxidized-vinyl-siding/

https://www.youtube.com/watch?v=tk5cma-AP8M

Without seeing exactly what the problem is, my first thought is to use a damp Mr. Clean Magic Eraser sponge to scrub the black away.

Hello. This link could be helpful.

https://homeguides.sfgate.com/oxidation-off-exterior-vinyl-trim-26874.html

I would use a Magic Eraser on it.

Here's a post that might help https://sciencing.com/methods-remove-oxidation-plastic-8716902.html

Hi Teresa, hope these help you out,

Mix together one part bleach to four parts water. Soak a rag or cloth in the solution and place the soaked cloth on top of the stain. Leave the cloth in place undisturbed for one hour to let the bleach soak into the stain and lighten it. Rinse the stain well with water and dry.

https://cleaning.lovetoknow.com/how-remove-stubborn-stain-from-vinyl-flooring

https://amzn.to/2QnL82l

Hi Teresa, hope these help you out,

https://sciencing.com/methods-remove-oxidation-plastic-8716902.html

https://www.youtube.com/watch?v=jOYdE8-8MmY

Hi! I recently cleaned some spots off vinyl siding using a soft bristle brush, hot soapy water and Soft Scrub. It took the spots right out. I have also used bathroom cleaners like Scrubbing Bubbles in the past. Good luck!

What do you mean black? is it a mold ?