You can "delete" many default apps on recent versions of iOS. (It doesn't actually delete them, it just hides them — the same as disabling an app on Android).
I don't think that document is entirely accurate. The apps "re-download" immediately, suggesting (to me at least) that they are still on-disk, somewhere. I believe that they delete associated user-data, though.
EDIT: Apparently things are different in iOS 11? Huh. TIL —
will have to try it out!
https://support.apple.com/en-us/HT208094