How to remove an unnecessary 404 page from Google Analytics?

Here in the dropdown you can see a 404 page, but i am not using it and don’t need it, it isn’t on my site but google analytics is telling me a 404 page is being found, when on my live site none of my pages come up with 404 so i dont know if this could be the problem?

is there a way of getting rid of it?

will these pages be indexed even if they aren’t being used on my live site?

Thanks

Ryan