Google Calendar: Clear the Primary Calendar

It isn’t possible to delete your primary calendar. However, you can clear the calendar of all events if you would ever want to start from scratch. To do so, follow these steps to clear your primary calendar’s events:

Clear your Primary Calendar Events

1. Log in to your Google Calendar. 
2. In the upper-right corner, click the "Settings' icon (gear-shaped gadget) > Select "Settings". 
3. From the side-panel, click the drop-down arrow beside the primary calendar you wish to clear from the "Settings for my calendars" section. 
4. From the resulting side-bar list, select "Remove calendar." 
5. From the "Remove calendar" section at the bottom of the screen, click "Delete."