Depends how deep stain has penetrated Paul, sanding top may not be enough, may need to deal with staining.
You could always try a strong bleach.
Give a good heavy covering and cover with a plastic sheet and press it on.
Works a bit like a poultice.
You can actually try a proper poultice, dredging memory banks here, mix baking soda and water to thick paste and apply, leave up to 48hrs. Wetting area first.
That’s if you can’t find an actual poultice paste locally.