How to delete old plugins?

As far as I understand Plex does not support plugins anymore. However I have installed several plugins, three of them show in the web interface (Subzero, FindMissing and ComicReader) but I can’t delete them using the web interface. All the other ones do not even show up in the Web Interface (Cine21, TVRage, Subliminal, …). And there ara another three folders I don’t even know if they are plugins or part of the system (Services, SiteConfiguration, WebManager).

So the question is what can I do? Can I just delete everything in the Plug-Ins folder?

Thanks.

P.S., Will Plex actively do something to stop people from using unofficial plugins (UAS)?

Yes, that is how you remove them. They cannot be removed from the Web UI.

Will Plex actively do something to stop people from using unofficial plugins (UAS)?

Eventually.