Trying to remove left sidebar from oxygen theme to create 2-column layout

Hello,

I really like Oxygen and don’t want to change my theme if I can avoid it. However, I’ve had several comments about it looking cluttered with 3 columns so I’d like to remove the left sidebar to create wider posts but keep the right sidebar.

I have tried updating the CSS as suggested in this thread: https://www.ads-software.com/support/topic/how-to-remove-left-sidebar-in-oxygen-theme but my site still looks the same, i.e. has 3 columns and a left sidebar.

Do I need to remove the code for the primary menu? If so, how do I do this without ruining everything? I am a beginner with CSS.

Is there another way? Again, please bear in mind that I am an idiot when it comes to code to I need very simple instructions if you are able to help.

The site I need help with is https://juliedawnfox.com/