Is it correct or ok to change default admin user id from 1 to any other number as done by better-wp-security plugin for wordpress for better security? what is best way for admin security. Thanks
You can change the original user to a non-admin, but I would not modify the admin users ID in the database to another ID, as this ID is referenced in numerous places, such as in the posts table to indicate the author, custom meta, user meta, etc
Instead, consider marking the admin as a subscriber, and reassigning the posts to a brand new user.
TLDR yes it will improve security, but mainly because you cant hack a site if it's completely broken