Put 3 tablespoons of salt in a bucket or large bowl.
Add water--enough to soak the entire top. Stir the salt water.
Put the top in the water and let it soak for about 10 minutes.
Take out the top and let it air dry. Now you should be able to wash the top in COOL water in the washer, and then hang dry it. However, I preferred to hand wash the op by taking a bit of laundry soap and scrubbing. It's up to you.