Just like Windows Vista, the admin (administrator) account is not active by default. You need to manually enable the default admin account. This may be required to make settings change or perform troubleshooting steps requiring admin rights and privileges. You can enable or disable admin account using a simple run command.
Enable Admin account
Click Orb / start button and open command prompt window with admin privileges. Then run the following command:
net user administrator /active:yes
Disable Admin account
Run the following command to disable admin account:
net user administrator /active:no