Unfortunately there isn’t such an option in PokaTheme 3.
If you want to totally remove the Sidebar, you should have a child theme (e.g. pokatheme-child) enabled. Then inside the child theme folder, create a file and name it “sidebar.php”, and leave it empty. This file should overwrite the default sidebar.php file of your parent theme (pokatheme), so instead of the sidebar you should see nothing in the frontend.
You are right, we haven’t added new features to CasinoAce for a long time, but we regularly check it to ensure it plays well with the latest WordPress version. We’re planning to release a new version by the end of the week.