Mix the stain-removing agent. Mix a tablespoon of dye-free or fragrance-free soap with 10 oz. of water. Swish it around to make it bubble and mix thoroughly. Then, place it in a spray bottle to help you apply it more easily to speed up stain removal.
Use a paper towel to carefully pick off as much of the extra marinara sauce as you can, doing your best to not rub the sauce into the fabric of the furniture or clothing it's on.
Aim the spray bottle at the stain about 6 inches away and soak the stained area with the diluted soap mixture. Then soak a cloth in white vinegar and pat the stain to remove more residue and the reddish color.
Soak a cloth in hydrogen peroxide and let it sit on the stain for a couple minutes. Wipe clean with a paper towel or dry cloth. Repeat procedure if the stain is still visible.