By default on Microsoft Windows 8 the Administrator account is disabled and you only have the personal user account created during the initial setup procedure done the very first time you opened the computer (or eventual other account manually created after).
Generally the user account you use should have enough privileges to perform any common daily routine, but sometime it is not enough and indeed you need to have the conventional Administrator account.
To enable the Administrator account, first you need to open the Command Prompt with administrative privileges:
Once you have the “Command Prompt” open, give the following command:
net user administrator /active:yes
And then close the “Command Prompt” with the command “exit“.
Now the Administrator account is enabled and available on the Start Screen.
If you ever want to disable it, the procedure is similar and the command you have to give is the following:
net user administrator /active:no