The plugins inside of Plugins are something of a microcosm unto themselves: inside of each plugin folder there is a Binaries, Content, Intermediates, Resources (kind of like Build, typically contains the icon for the plugin), Source, etc… Same rules apply, if you have source code you can delete Binaries and Intermediates, but if it’s a plugin from a 3rd party that you don’t have source code for then you should leave Binaries alone.
Cheers,
Michael Noland