When Mac OS X El Capitan debuted in 2015, for the first time in the Mac operating system, you could hide the menu bar. This continues in macOS Catalina. I’m not sure why you would want to, but if you do, here’s how:
Hide the Menu Bar
1. Open System Preferences.
2. Click on the General icon.
At the top of the new window, you’ll have several options under the Appearance listing.
In addition to enabling or disabling the dark menu bar and Dock, you can choose to “Automatically hide and show the menu bar.” Click this box and the menu bar vanishes. It will show up again when you glide your mouse arrow towards the top of the screen.
Show the Menu Bar
Don’t like it? To make the menu bar stay visible at all times, uncheck the “Automatically hide and show the menu bar.”