Over time, all of your saved calendar items might add up to a large number and occupy a large amount of space in your data file. To free some of this space, you can reduce the number of saved items by archiving or deleting them.
What do you want to do?
Archive your calendar items
The archive process deletes items from your data file after first making a backup of the items in another Outlook data file.
Click the File tab.
Under Mailbox Cleanup, click Cleanup Tools.
Note: Some organizations turn off the ability for users to create Outlook Data Files (.pst) which are used for archiving items. If you do not see Archive command, your organization may have turned this feature off.
Click Archive this folder and all subfolders.
If you created additional calendars, selecting this setting will archive items from those calendars as well.
In the folder list, click Calendar.
In the Archive items older than list, select the date that you want. To archive everything, select a date in the future.
If you want, select the Include items with "Do not AutoArchive" checked check box.
Selecting this check box will archive everything, including items that you marked as exceptions to AutoArchive.
You can accept the file location where the archive file will be saved, or you can browse to a different folder and provide the file name of your choice.
Note: We recommend that you make a note of this location so that you can easily find the archive file later.
The archiving process begins. When you return to the main Outlook view by clicking the Home tab, the Outlook status bar indicates that the archive is in progress.
To cancel the archive in progress, click . Any items that were already archived up to that point will remain in the archive file.
Delete all items on your calendar
The process of deleting removes all the items from your data file without making a backup.
Warning: The following steps will delete all items in your calendar, including holidays that are automatically added to the calendar. You can replace default Outlook holidays that are deleted during these steps, but all other calendar items will be permanently deleted.
In the Navigation Pane, click Calendar.
On the View tab, in the Current View group, click Change View, and then click List.
Click in the item list, and then press CTRL+A.
All items in the list should now be selected.