How do clean up black mold off of drywall?

Was the drywall finished and painted? Vinegar can remove mold. However, if it's black mold I don't think I would risk it. There is a very good chance the insulation and studs behind the drywall has mold as well. You can get very sick if it isn't all removed.

Wash down with vinegar and water. Spray with Lysol mold killer. Let dry, prime with stain blocker primer like Kilz and paint.

Spray with bleach and repeat let dry in between applications . 1 part bleach 3 parts water.

How much? Chances are you might have to call the pros in as this is highly regulated by the EPA.

Vinegar does the trick, bleach doesn't kill mold spores.

https://www.servicemaster-restoration-cleaning.com/2017/03/30/mold-myths/

https://www.servicemasterrestore.com/blog/mold-damage/mold-myths-will-vinegar-kill-mold/

https://restorationmasterfinder.com/restoration/what-kills-mold-bleach-vs-vinegar/

http://www.aboveandbeyonduc.com/moldblog/professional-vs-diy-mold-remediation-when-to-call-in-the-pros/

Honestly, removing the sheetrock and making sure the mold hasn't spread is a good idea.

Hi Crystal - There are several ways to get rid of mold, but most importantly, you need to address the root cause to keep it from returning. This article focuses on the bathroom, but is an overall great article that covers methods of how to remove mold, if bleach is safe to use, and how to prevent it from coming back. Hope this helps! Hugs, Holly

https://pinkfortitude.com/mold-in-the-shower/