That's not what I told you to do.
As I've explained, the WMIC command needs to be ran as administrator. This is something that must be explicitly used even if your user account has administrator privileges (yes, it tripped me too).
This is why we're going through creating the batch file. Once you have the batch file, you can right-click it, then choose "Run as administrator" from the context menu without having to go through any additional trouble or entering any further commands.
You saved as a text file. After selecting "All Files", you need to make sure that at the end of the file name you've entered, there is a dot and BAT written after the dot ( .bat ). That's the file extension. Without that extension, your OS will not treat it as a batch file.