If you'd like to remove older data from your calendar, it can be time-consuming to delete each event. You can use the export-import functionality to quickly remove data you no longer need on your calendar.
Open that file in Excel and check that all data is there.
Deactivate all relevant sub-calendars in your calendar.
In Excel, delete the events you'd like to remove from the calendar.
Import the remaining data back into your calendar. You will then be left with only the events you want to keep on your calendar.
Imports cannot be undone. So, test this process out before proceeding on your calendar.
Create a test calendar by generating a Live Demo calendars. Test the process by exporting data from your calendar, then importing to the live demo calendar.
Deactivate the sub-calendars containing old data you want to remove rather than deleting them. This way, if the import does not work as expected, you can reactivate those sub-calendars to try again.
Once you have successfully completed the export-import process and are happy with the data that remains on your calendar, you can delete the original sub-calendars.