Scratching is a normal part of cat behavior and serves several functions, including conditioning of the claws, providing a means of stretching, and acting as a marker (both olfactory, or scent, and visual). Cats like to scratch! The act of scratching actually removes frayed and worn outer claws, exposing new, sharper ones.
Cats tend to pick a small number of conspicuous objects in their environments to scratch such as trees, fence posts, the corner of the couch, etc. and return to them repeatedly. This is why the tree next door looks so scratched up and why your cat may find it difficulty to leave your couch alone. The scratched surface leaves a highly visible mark that can be easily seen by other cats. In addition, cats have scent glands in their paws so that when they make scratching movements they leave odor cues that the cats can smell. The fact that cats leave scent marks by making scratching movements may be the reason that cats will continue to try to scratch objects even after they have been declawed. Declawed cats may still be leaving scent marks on objects they scratch.
In some cases, keeping the cat away from the area that is being damaged is the simplest solution to the problem. Another variation is to allow the cat to have access to whatever is being scratched inappropriately, but to make that area unattractive to the cat while making a more appropriate area more attractive. Many the couch because they simply do not have another option to exercise their scratching needs. All cats have a need to scratch and should be provided with appropriate posts to do so. Hopefully, your cat is not scratching but you are trying to pre-empt a problem.
Cats dont understand physical punishment, so hitting me when you catch me scratching on your leather couch is not going to help. Cats like rough surfaces that they can shred to pieces well, you probably already knew that. The solution is to provide legal scratching toys and play with your cats on them so they understand it is ok to scratch there.
Put your and toys in the main areas of traffic flow, where you hang out a lot of the time. Most cats wont make it to the back bedroom when they feel the urge to scratch. Pretend that youre scratching the surface, attack the surface, and encourage your cat to play with you. Its been proven you can actually train your cat to scratch in appropriate places. So start scratching with your cat.