Could a Atheist sin?

I came upon this question while scrolling on YouTube. It was how could an atheist sin even though he doesn’t believe in God. With sinning you’re disobeying God but if you don’t believe in God how could you disobey. Whether you’re actions are moral are not (depending on your beliefs) one could do an immoral act but not sin since he is an atheist and doesn’t believe God exist,thus, they could not disobey God.