Delete all events from calinder (before import)

Hi. We re migrating out google calendars to our owncloud server and i've been testing the best way to do it. i worked it out, its very easy. Thing is now I have the calendar imported and want to clear all the events out to do the real import. Looking around, and testing, shows importing twice creates duplicates, and there is no clear out everything first option. So how do I delete all events from a given calendar?

I think, the easiest way is to import into a new calendar and then delete the old one.

However, I could also clear my calendar with Thunderbird/Lightning. Use Find events->All Events, select the entire list of events and delete them.