Question
How to purge the Configuration Management Database of unwanted/outdated data

Answer

In the Symantec Management Console menu, click Settings > Notification Server > Purging Maintenance

on the Purging Maintenance page
on the Purging Maintenance tab

You can specify how the Notification Server (NS) should handle information about managed computers that have not communicated with the NS for longer than a specified amount of time.
You can specify whether the NS should purge all data about these computers, or just mark the computer as "retired."

For example, you can purge information about computer which have not checked-in in the last 6 months.

on the Resource Event Data Purge Settings tab

You can instruct the Notification Server (NS) to purge older information collected about managed computers.
You can specify that the data should purged after a certain amount of time or after a certain number of records/entries.
Additionally you can specify different settings for different types of inventory data.