To Delete all the calendar from outlook 2010, please try this:
1) Click on the ‘Calendar’ tab in the Navigation pane.
2) In the calendar window thus opened, click on the ‘View’ tab and then under the ‘Current View’ category, click on the drop down arrow of the ‘Change View’ icon and then choose ‘List’ from the drop down list.
3) Now a window that contains all the Calendar entries appears on the screen. In this window of entries click on an entry and then press ‘Ctrl+A’ to select all the entries in the calendar.
4) Once you have selected all the entries in the calendar, press Delete button and all the calendar entries will be deleted.
So, this is how you can delete all the calendar entries from the calendar of MS Outlook 2010 Application.
Here’s to Good Karma