How do I delete a single calendar in Android (not just hide it)? How do I delete a single calendar from the native calendar app (not only the entries: the whole calendar) without wiping out the app or all calendars, in android >4.0?

This feature was available till ICS. In Kitkat, it's still not possible.
i just ran into the same problem. I  created a local calendar with an app and then removed the app before deleting the calendar. I could re-install the app and delete the calendar there. So for you as a developer this means you should probably add this functionality to your app.

However if you need a quick fix or if someone else is running into this problem with a third party app that does not provide a way to remove its own calendars, you can use the (no longer free) app iCal Import/Export CalDAV by Lukas Aichbauer, as this app allows you to remove any local calendars. 

Just start it, select "Edit Calendars", then "Choose Calendar", and select the calendar you want to remove. Then click "Delete Calendar" and confirm if you are certain you have selected the right one.

Maybe use the same app first to pull a backup of your calendars you want to keep.

EDIT: in response to raphadko's comment, i've updated the link, the app still exists but is no longer free