Help with smell of animal urine/feces

[Nancy Zhao]

I've rehabbed quite a few homes that were garbage dumps but this one takes the cake. This property has probably dozens of rats inside with piles of rat poop everywhere. The smell is so overwhelming that even with a mask it's unbearable.

Has anybody dealt with something like this? What's the process to remove the stench? I'm open to anything including removing all the floors. Any advice would be much appreciated!