Hello Android,
Unfortunately, you cannot change the name of a
C:\Users\(user-name) user folder. The only way around this is to create a new account of the same type (ex: administrator), then copy all of the contents from the old account's
C:\Users\(user-name) user folders (including
hidden AppData folder) into the corresponding new account's
C:\Users\(user-name) user folders. After everything checks out ok, you can then delete the old account from while logged in the new account.
Hope this helps,
Shawn