Because of their size, hornworms are easy to pick off and discard.
They’re an excellent source of protein for chickens, if you raise your own flock at home, but you can also simply drop the hornworms into soapy water to destroy them. (I keep empty coffee cans and yogurt containers around for this reason.)
Remove them one by one and either smush them, drop them into a can of soapy water, or collect them in a jar to feed your chickens. (Don’t forget to check your other nightshade plants too.)
If you see a hornworm on your tomato plant with tiny white “rice grains” attached to its body, leave it alone. It’s been parasitized by braconid wasps, and those white things are their cocoons.
Flowering tobacco (Nicotiana spp.) is a highly fragrant flower that’s part of the nightshade family. A few species are quite attractive and make a beautiful addition to a flower garden.