Our screen is next to the bathroom door. Mold is building up due to the moisture. What chemical do I use?

I can't help you with the screen, but as for mold prevention I would replace or add a vent fan to your bathroom.
You shouldn't be getting that much moisture build-up.

If you've got mold building up on your screen you've got more problems than mold on your screen. Get that vent installed like Nitrogen_Widget said.

Aside from seriously needing a venting system you may be in for some problems.
There are some screen materials that cannot be easily cleaned. Glass bead comes to mind first. Your best bet is contact the MFR and ask them the best way to approach it. They may have some foolproof ways for you to do it.
But I would estimate the chances of being able to remove the mold without problems with the screen at less than 10%.

Good luck and let us know what you find out.

SJ

I would try to dry it with a hairdryer. Just keep moving to not heat 1 spot too much.
You can try it on a small area.
You should be able to dust it off with a soft brush.
Depends a lot on the material and how long the mold is there.