How to Change Account Name in Windows 11 Pro

Restart the PC
Login as a secondary Administrative account
Go to Control Panel and rename the account
Set/Change password for account
Rename the Directory from C:\Users\OldUser to C:\Users\NewUser
Go to the Registry Editor and change the account name.

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\S-1-5-21-1016846037-3682850039-186600283-1001 (Replace this with the correct Profile)

Then Restart the computer