How to delete all Google Calendar info

I have a Pro account and have been syncing my Google Calendar. I'm not liking the way it is syncing, and it's messing up my Google Calendar. I'm tired of it importing all events and also making them into tasks, that way they are listed twice.  And if I delete the task part and just keep the event in my WeekPlan, it somehow deletes the event all together on my Google Calendar. I'm frustrated and just done with it.  Now that I've asked it to disconnect from my Google Calendar, all of the events are still showing up on "My Week"...how can I delete all Google Calendar data (without messing up my Google Calendar itself)?

This needs to be fixed.