What should I use to kill mold?

ALWAYS WEAR A RESPIRATOR!

Heat the structure to it's thermal kill point.

(Use air purifier for next steps)

Remove any severely affected areas like drywall and carpeting.

Spray and scrub all framework with a mold repellent.

Wipe down all walls with the repellent.

Install dehumidifier to keep relative humidity below 50%

Or call a professional to do this for you since they have all the tools on hand and will guarantee their work against regrowth. (not all companies use these steps but it's the BEST way to ensure the problem is gone make sure to ask A LOT of questions so you don't get taken advantage of and that they warranty their work.)