So, recently I was re-building my website, putting on another CMS, optimizing and so on. Now I visited Google Webmaster tools and it tells I have a lot of Web crawler 404 not found errors.
I am keeping almost all URLs for Articles the same. Almost all the errors now come from insignificant pages that I removed: Archive/date/ and user profile pages. I don't plan to re-create those auxiliary pages for robots now or in near future, but 'never say never'. I know Google crawlers sometimes do crawl some pages for several years while they are long time gone.
Yesterday night I submitted for removal as outdated content several really old non-existing pages crawled for at least some 3 years, but I still have several hundred 404 error pages now. I don't know if I should I submit to remove them all or not.
There may be a small possibility that I may need some of those URLs in the future. If I remove them now, what would happen if I need this URL for something again?