Redirecting to the home page is about the worst scenario here. Some possibilities would be to: 1. 301 redirect individual pages to similar pages with updated or similarly-relevant information
2. send a 404 Not Found error response, and use a custom 404 page with a site map, links or search box to direct users to other pages of your site (otherwise they are likely to simply click the Back button and go elsewhere)
3. Use a 410 Gone response code - technically this will probably be the "correct" response code, but search engines generally treat it as a function equivalent of a 404.
Personally, if I couldn't redirect to replacement content, I would go for a 404.
