There are a few ways to neutralize red stains, depending on the type of fabric and the severity of the stain. For example, if you have a red wine stain on your shirt, you can try blotting it with white vinegar or club soda. If the stain is more stubborn, you can mix equal parts baking soda and water to form a paste, then apply it to the stain and let it sit for 30 minutes before washing as usual.
If you have a red lipstick stain on your collar, baby wipes are surprisingly effective at removing them. Just be sure to test the wipe on an inconspicuous area of fabric first to make sure it doesn't damage or discolor the fabric.
For tough stains like blood or grass, hydrogen peroxide is usually your best bet. Simply pour some hydrogen peroxide onto the stain and let it sit for a few minutes before laundering as usual. You may need to repeat this process a few times for really stubborn stains.