If you have a fresh blood stain on plastic, the best way to remove it is to rinse it with cold water. You can also try blotting it with a clean white cloth. If the stain is older, you may need to use a little bit of soap. Apply a small amount of liquid dish soap or laundry detergent to the stain and scrub gently with a soft-bristled brush. Rinse well with cold water and dry the area completely. You can also try using hydrogen peroxide on tough stains. Pour a small amount of hydrogen peroxide onto the stain and let it sit for about 30 minutes before rinsing away with cold water.