The best thing I've found after dealing with mold is a simple 3% hydrogen peroxide solution that is sold in any drugstore. Put it in a spray bottle and soak the area deeply enough and it should kill it down to the roots.
And a plus is that when it breaks down the only fumes it gives off is pure oxygen, unlike other cleaners like bleach. It did such a good job that I use peroxide as a general purpose cleaner now.
I will add one note that you should rinse your hands regularly if cleaning with peroxide. Just a few days ago I had a leaky spray nozzle, and the peroxide was on my finger long enough that it was able to soak in. It turned my skin chalk-white and caused an uncomfortable bubbling sensation inside my skin. I had no idea it was even a reaction that could happen. It only lasted for a few hours, but it's not something I would want to happen again.
And a plus is that when it breaks down the only fumes it gives off is pure oxygen, unlike other cleaners like bleach. It did such a good job that I use peroxide as a general purpose cleaner now.
I will add one note that you should rinse your hands regularly if cleaning with peroxide. Just a few days ago I had a leaky spray nozzle, and the peroxide was on my finger long enough that it was able to soak in. It turned my skin chalk-white and caused an uncomfortable bubbling sensation inside my skin. I had no idea it was even a reaction that could happen. It only lasted for a few hours, but it's not something I would want to happen again.