If you want to use Facebook without dealing with private messages, your options are somewhat limited. Years ago you had the option to block the message function. These days about all you can do is shut off annoying chat notifications that interrupt your browsing or block individual users.
Let’s take a look at how to stop that chat window from popping up. Open Facebook in a browser and chat icon at the top of the page to open Messenger.
Click the three-dot icon at the top of the window to open Settings.
You can mute the sounds for incoming calls and also change the settings so new messages won’t pop up on your screen. Those messages will still go into your inbox. You can select Block Settings to prevent certain individuals from contacting you.
You can then block messages from individual friends by adding their names. If you wanted, you could add the name of every single one of your friends to prevent any messages. Not a completely satisfactory solution for those who don’t want any messages, but the best I have for now.