Moesia Theme – Can't remove/hide the sidebar. HELP please!

I am a bit technically challenged and have spent hours trying to figure out how to hide the sidebar on individual pages. I reset each row of the pages to “Full Width”. Still does not work.

I read some old post where people advised to add the code below to the CSS.
.site-info {
display: none;
}

Where do I find the CSS code (I played with the Customizr and there is an advanced function under “Customize” but I can’t find it there for Moesia.

Here is the website: https://curativeconsulting.com/about/

Many thanks for any help!