Generate report to detect inactive users

I am building a site exclusive to local residents. Unfortunately, people will move and then stop using the site. So I want to list people who haven't logged in for, say, a year and delete them, but I can't find a built-in report that lists last logins. It sound simple in principle, but as a Drupal beginner I can't work out how to do it for myself. Any pointers would be much appreciated.