Hi,
To remove the archive Data you can select the Retention Category option in the policy. (Retention Category Tab).
For that Retention Category set the Retention Period. So after that Retention Period the archived data will be deleted from storage with help of Storage Expiry option at EV site properties.
If you change the Retention Category option in the old policy , it will apply on your old archived data. If we change / modify the setting in old policy it wil applicable to old data.
You can use FSAUtility with the -o parameter to delete orphaned placeholders for which no corresponding item exists in the archive.
FSAUtility -o -s UNC_path [-l log_level] [-r]
Articles :
About FSAUtility
http://www.symantec.com/docs/HOWTO57806
FSAUtility options
http://www.symantec.com/docs/HOWTO57559