I think most homeowners would just assume they have to clear the public sidewalks adjacent to their homes. My dad did it when I was growing up (I’m sure he still does). I see my neighbours doing it on my street (thank you!). As for me, once I had my own house, I just presumed I had a legal duty to do so. The actual, real answer to the question is a very typical lawyer answer. You MAY have to clear the public sidewalk…but it depends on the circumstances.