Brown Flip Flops My Rainbow Flip Flops Left Brown All Over The Bottom Of My Foot. How Do I Get Rid Of This?

My rainbow flip flops left brown all over the bottom of my foot. how do i get rid of this? - brown flip flops

my rainbow. I have had one or two years, and left the red-brown stuff coming. I tried soap, shampoo, conditioner, what should I do?