There are now a official plugin with similar(and additional) functionality as this plugin, I would recommend using that instead:
"privacy-remover"
Sourcecode: https://framagit.org/framasoft/peertube/official-plugins/tree/master/peertube-plugin-privacy-remover
NPM: https://www.npmjs.com/package/peertube-plugin-privacy-remover
Screenshot from "Plugins/Themes" administration page:
Disables "Public", "Unlisted", "Private" and the option for password protection under Privacy on the publish/upload page, making the "Internal" setting the only available option.
Use latest version (1.0.3) for PeerTube version 6.0.3 and higher.
For older versions use plugin version 1.0.0.