You want to use the Plugin Manager which allows you to create Collections that only show you the plugins you want to see. it also has an information section at the bottom which can be opened or closed. When open if you select a plugin you’ll see the pathname to its file. You can actually do quite a bit with it, so it’s worth taking a peek at the manual.
Hi. Just open plugin manager, highlight the ones you want to get rid of and hit Delete. It would be better to follow Raino’s advice though, and leave the default collections alone and create your own custom one(s), even if it’s the same or nearly the same as the default. That way you always have the complete set as backup.