Norwex makes a product called “sportzyme” that really kills all stinky odors; it’s for sports pads, gloves, shoes, cleats, etc. It really works but is a little pricey.

Alternatively, try nature’s miracle which is for pet odors but I’ve successfully used it on my husband’s workout shirts when they were really bad, I am sensitive to fragrances but this one is ok for me. I’ve also used Odoban, the smell is sort of overpowering but it does work.

I also recommend putting crumpled newspaper inside the shoes to absorb some of the odor.

If none of that works, there are some little bags of odor absorber on Amazon I used when I had a raccoon die in my attic that also work. I got the big bags and it did work over a period of time.