Hello Anon, and welcome to Seven Forums.
Sorry, but you cannot change the name of your
C:\Users\(user-name) folder itself. Doing so will most likely give you a user profile cannot be loaded error.
The only way around this would be to
create a new administrator account with the name you like, then copy all of the contents of the old user account's
C:\Users\(user-name) folders (including
hidden AppData folder) into the corresponding new account's
C:\Users\(user-name) folder. After everything checks out ok, you can delete the old user account while logged in the new user account.
Hope this helps,
Shawn