The built-in Guest and Administrator accounts are well-known user accounts on all Windows systems and, as initially installed, do not require a password. This can allow access to system resources by unauthorized users. It is best practice to rename these accounts to an unidentified name which improves the protection of those account and the system.

https://www.stigviewer.com/stig/windows_10/2018-04-06/finding/V-63625
https://www.stigviewer.com/stig/windows_10/2017-02-21/finding/V-63619