how to delete all locally saved calendar events from iphone

My icloud calendar events were not synching properly, so in an effort to fix the problem, I signed out of icloud, saving a copy of all events locally on my iphone as I did so. I signed back in to icloud and all my events synched nicely. Now I'm stuck with two entries for each and every event on my phone going back as long as I've used icalendar. Is there a simple way to mass delete all locally saved events? Then I will only have the one version from icloud.

Any useful suggestions would be greatly appreciated!