Hi

If you select the cog wheel icon at the bottom of the sidebar launcher, you should see an option to "Show and hide sidebar". Selecting this will hide the sidebar.

I don't mind a sidebar. I actually always keep the Bookmarks Toolbar open. My issue is the new wasted space that has been added to the side of that for icons. That is the space I want to eliminate. Is that possible?

Yes - I've found how to get rid of it but my question was why is it necessary to keep changing things for no obvious benefit?

Another browser (maybe Opera?) pioneered this left-side button bar and vocal users asked for it in Firefox for many years. So you probably have them to thank/blame.