Enable the Hidden administrator Account in windows 7

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)

Now 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.

You’ll note that there’s no password for this account, so if you want to leave it enabled you should change the password.

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. Type the following command:

net user administrator /active:no

The administrator account will now be disabled, and shouldn’t show up on the login screen anymore.