While it's technically possible, it is probably not a good idea. You would have to audit all the code on your system to check if any of it has the root user name hard-coded.

While the recommended practice for e.g. shell scripts is to check the user ID (if it's zero, you are root ) or check for the actual privilege you require (if you can write a file where you want to, who cares which precise user you are running as) but not all programs adhere to the recommendation. (In fact, the installers and/or packaging scripts for many popular commercial software packages contain some truly atrocious shell scripting.)