Rabbits groom themselves like cats do, and don’t need to be bathed. The only exception to this is when rabbits with “poopy butt” may need to have a butt bath, which only involves cleaning the rabbit’s genitals and hind quarters. We have a great video that shows you how to do this.
Please do not give your bunny a full body bath. This can be extremely traumatic for a rabbit and can put them into shock; many rabbits have died from this kind of trauma. While you may have heard of rabbits who like to swim, most rabbits do not tolerate being submerged in water, and the shock of it can be deadly.