Premiere RUSH separating audio

So a bit confused. I see on this Adobe site, there should be the ability in Rush to seperate the audio from the video file. https://www.adobe.com/creativecloud/video/discover/remove-audio-from-video.html

I am trying to record a game with my in game talking and seperate them to edit each with different volumn levels etc. But I cannot see the option to do so. The link to the Adobe site above shows, right click and it will give the option to seperate audio. There is no such option for me, just expand, duplicate and delete. What am I doing wrong?? 

Thanks!