I found that I have a lot of unknown 3rd party plugins installed in my Mac.
I thought they are Safari extension, but Extensions popup menu in Safari do not show these extensions.
How to remove these unknown extensions? I don't remember I install some of the extensions (especially those Chinese extensions); how come they ended up in my Mac?
Best Answer
They're built-into the OS. Just leave them switched off & ignore.
See how to delete extensions Youku, Tudou, etc... which pretty much says the same thing. Especially pay attention to anything Linc Davis ever says; he's the closest thing to an actual authority on the Apple forums.