Yes indeed it is wrong to declaw a cat full stop. Declawing a cat is specifically what to NOT do with a problem cat!
Cats will scratch their claws, as it's a perfectly natural behavior. This is because it's done to scent mark their territory, as well as keep their claws sharp and healthy for hunting, down to their natural instincts as hunters in the wild.
Declawing a cat doesn't just mean removal of their claws. It's also amputating the last digit of the toes, which is the equivalent of cutting off the distal phalanges of the human toes or fingers and thumbs, which is painful for the cat. In many cases, it can also lead to problems like inappropriate elimination (toileting outside of the litter box) since they won't want to dig in the litter with sore paws. That plus at times, people do it to stop an aggressive cat from scratching, but this leads the cat to become hyper aware of what they have left. They typically resort to scratching with their back claws, and they will also bite a lot more than they otherwise would.
Put the back of the scratched couch by a wall so that it can't be seen, and make sure you give the cat at least one scratching post to use, preferably a tall one which will allow them to stretch while scratching their claws more. You may find it helpful if you rub some catnip on it (since some cats like the scent), praise the cat for using it, or give the cat a treat if you see them using it, especially a treat which they particularly like. That way, the cat will learn that it's perfectly okay for them to scratch their claws on the scratching post, but scratching their claws on furniture isn't.
To further put the cat off scratching furniture, use furniture cleaner which has a scent which cats typically dislike, such as strong chemical, citrus like lemon or orange, or coffee. Rubbing pepper sauce on wooden furniture can also repel the cat as well.
Hope this helps.