If you want to activate the administrator account in Windows 8 to perform administrative actions, you will need to run a few commands via the command prompts. Here’s how.
1. Step Open an elevated command prompt as admin in Windows 8
2. Step If the first step fails and you open a regular command prompt the next step is not going to work, so make sure you actually open an elevated CMD as described.
3. Step The command prompt should be opened at C:\Windows\system32
4. Step Enter net user administrator /active:yes to activate the admin account
It should say “The command completed successfully” or you did a mistake (post error messages below)
5. Step You should now log off Windows 8 and on the Windows 8 logon screen you will see the activated administrator account that is normally hidden. This hidden admin account should only be used for maintenance purposes and not as your regular Windows 8 account, keep that in mind.
Or when you click on the username on the Metro desktop you simply click on the Administrator link and you will automatically log into the admin account: