Installing the WP Date Remover Plugin is helpful because you can go update or rewrite older posts and pages instead of deleting them.
If you delete them then if people have linked to them, anyone following those links will meet with an error page. You can also do redirects. But by rewriting the article with updated information you can keep those links going without the errors or redirects.
View video tutorial below article on installing the WP Date Remover.
Since the posts and pages do not have the original dates your new, current information won’t be in conflict with the older dates.
Install WP Date Remover Plugin Using These Steps
Go to your Dashboard to Plugins and to Add New.
In the search box type “WP Date Remover” and click to search.
Click to Install and Activate the Plugin.