Deleting old eventsCalenGoo does not contain functions to automatically delete masses of events. To delete events, you have to select them one by one. But if you would like to delete e.g. all old events from your Google Calendar, you can use the Java program here:
Start MassDeleteEvents using Webstart
But before you use it, you should download a backup copy of your Google Calendar: Sign in to Google Calendar and click the gear icon in the upper right corner, “Calendar settings”, “Calendars”, “Export calendars” to download a ZIP file that includes all your personal calendars as ICS files. Unzip the file and ensure that it contains these ICS files.
If you used the Webstart link above, it should start automatically. If it doesn’t start, try to double click one the downloaded .jnlp file. And ensure that Java is installed on your computer. If you don’t have it, you can install it from http://www.java.com.
After starting it you should see this window:
Enter you email and password and click “Sign in” (if you are using Google’s "2 step verification" you have to generate and use an application specific password instead of your normal password). Wait for a few seconds and then select a calendar on the left. Afterward enter a date in the “events before this date” field and click “Search old events”:
It will display all old events it has found (except recurring events).
Now select the ones you would like to delete. You can select multiple entries by clicking with SHIFT or CTRL or you can select all by clicking on a single entry and pressing CTRL-A/CMD-A. Ensure that the selected events are really the ones you wish to delete. If you are sure that you selected the correct events, click “Delete all selected events” to delete those events:
Now click “Refresh” in Google Calendar to see if the old events have been removed.