Archiving the Calendar: Part of the mailbox space on the mail server is taken up by the calendar. People who use the calendar extensively may find they have less room for email. The quickest way to recover space is to Archive old appointments.
Archiving moves old appointments to a PST (Personal Folders) file, so that they can still be looked up, but removes them from the mail server. Archiving calendars may also have a side effect of speeding up Outlook.
File > Archive
Select the Calendar
Set the date you want to archive to
Choose a file location
Select the Calendar
Set the date you want to archive to
Choose a file location