Check that shoes are fabric and not leather. FIll sink with hot soapy water. Add ¼ cup bleach. Slosh and stir around. Rinse. Put outside in sun.

(Why do you want bleached shoes?)

Bleaching may reduce the life of the shoes if you use too much. It weakens the fabric. I’d try washing them in the washing machine in warm water with laundry soap that contains whitener. Or scrub them with a toothbrush a very mild bleach solution. We used to use white shoe polish to make them whiter.