Enable Built-in Administrator Account
First you’ll need to open a command prompt in administrator mode by right-clicking and choosing “Run as administrator” (or use the Ctrl+Shift+Enter shortcut from the search box).
If you are in Windows 8.x you can right-click on the Start button and choose command prompt (Admin) to open a command prompt.
Then type the following command:
net user administrator /active:yes
You should see a message that the command completed successfully. Log out, and you’ll now see the Administrator account as a choice.
Note : You’ll found that there’s no password for this account, so if you want to leave it enabled you should need to change the password for security reasons or keep as your own risk.
Disable Built-in Administrator Account
Make sure you are logged on as your regular user account, and then open an administrator mode command prompt as above steps .
Type the following command:
net user administrator /active:no
Now the administrator account will be disabled, and shouldn’t show up on the login screen anymore.
