If you don’t mind them being gone from everywhere, you can disable them here:
https://app.plex.tv/desktop/#!/settings/online-media-sources
Set Movies & Shows, Live TV, and Discover Source to “Disabled” (not Disabled for Managed Users). This will remove the On Demand, Live TV, and Discover tabs from the nav bar. It will also remove all of those services’ related content from the home screen. This effectively removes all Plex-related online content. You may need to restart the app for this to take effect.
As mentioned however, this is an account-level setting. So those sources are also removed from all other clients. If you’re instead looking for a way to customize it on the client itself, that’s not possible (as of right now).
As of version 2025.14.0 there’s now a hub below the Continue watching hub which provides access to your favorited libraries (on mobile devices at least). It’s not a customizable nav bar, but it does place the libraries closer to hand.
