Taking it a step further, you can actually completely disable all of the Plex content that’s unrelated to Nevflix. To do so, navigate to settings on the plex.tv website. Then go to “Online Media Sources” and hit “edit” on every item listed on that page and change from “Disabled for Managed Users” or "Enabled" to “Disabled”.
Of course, if you’d like to keep any of these enabled you can pick and choose. I personally recommend to disable all as to not interfere with the content on Nevflix. Keep in mind, any movies or shows Plex offers are ad-supported, as is their Live TV function that doesn’t have any significant channels.