The answer to this is no, a microwave cannot reliably kill or deactivate mold.
Mold is a fungus whose colonies can grow to be large relative to your microwave. Mold is not like bacteria or a virus that can be deactivated at high temperatures.
It is also not like bacteria or a virus in the sense that they are microscopic and invisible to the human eye. Mold is large, visible and must be cleaned out of a microwave.
The best way to treat mold is to use vinegar whose high acid will kill the mold then scrub the mold away until it is completely removed. Even if you could kill it, you run the risk of letting byproducts or toxins remain in your microwave if you don’t fully clean it out.
Also, if the mold keep reappearing then it is probably in the walls of your microwave and it’s time to buy a new microwave (and begin a new resolution on keeping your microwave clean and dry!)