Calendar Cleanup:

Here's another quick tip to help you reduce the size of your mail file.
Often, you don't need to save old calendar and to do entries. After a certain period of time has passed, you probably won't need to refer back to a calendar or to do entry. So Notes has a feature that deletes past entries that haven't been modified in a long time. You can select how old the entries need to be, and whether to delete calendar entries, to do entries, or both.
Note: Calendar Cleanup deletes calendar and to do entries permanently. If you want to be able to go back and review the entries later, you can either remove them from your Inbox, or archive them.
To use the Calendar Cleanup feature, follow these steps:
1. Open you calendar.
2. Click More > Calendar Cleanup (0r) Tools > Calendar Cleanup.
3. Choose the entries you'd like to delete. Advisable to choose all calendars and to do entries older than 6 months, but you may want to do something different.
4. After you click ok, Notes will delete all entries that have not been modified in the time you specified.