As rodents, squirrels have teeth that never stop growing. To wear them down, they need to spend a lot of time chewing. Sometimes squirrels choose wooden window frames, outdoor furniture, or other surfaces as favourite chewing spots.
How to get squirrels to stop chewing on furniture or windows
To get a squirrel to stop chewing on something specific, make it taste bad. Commercial capsaicin or bitter apple sprays are effective. Rubbing the area with a very perfumey bar of soap will also work.
Yelling at the squirrel to get lost every time you see it will also be effective—squirrels aren’t very strongly tied to their favourite chew-spots, and they’ll find somewhere else to go if they don’t feel comfortable.