The question would be Why do you want to do that:
to clean them.........leather is skin:
bleach is acid:
the result is you kill the leather:
Use professional leather cleaners..........again white shoes will never be perfectly white after you wear them ever again:
because white dye doesnt sink into the leather like black:
it is like a paint on the surface and it simply sits on top of the leather and is worn away bit by bit:
You can take them into a shoe repair to have another coat of white dye applied to extend their life.