Right now, you can remove custom fields from layouts and HIDE default views. However, when you "hide" them, people can still see them in the records, they just have to click "Show More". This was confusing for us AND Aha staff who tried to figure out the issue. The user interface makes it seem like "show more" will show you more fields that just couldn't fit in the scrolling page.
Some of the default fields cause a lot of confusion for our teams and we would like to be able to completely remove them.