Sometimes you might have noticed that the username being displayed, when signing in a Microsoft Account in Windows 10, is not what you want it to be. Fortunately, Windows has the feature which allows us to change account username in a simply method.
1. Right-click Start icon at the bottom left of the screen.
2. Next, click Run in the pop-up window.
3. The Run dialog box will display, then type the following commands in the box of Open: netplwiz. Do not forget to click OK.
4. The User Accounts window pops up, double-click Administrator, which is under Users for this computer.
5. Here comes the Administrator Properties dialog box, go to General tab, then you can input whatever you prefer in the box of User name, simply click OK and the account user name of this device has been changed accordingly.