You cannot bleach carpeting. It's usually made of synthetic materials. Those do not "bleach". Even if your carpet is made of 100% cotton, the amount of bleach you would need would be toxic. There's no way to remove it once you dump it on the floor. That would make you very ill. IF you want white carpet, pull up the old and replace it with white carpet. Trying to change the color of your carpet with chemicals is a horrible idea.