The purge process is fairly simple ...
To run the purge you'll need to know the SiteID from the Database. This can be found from within TERMS - Maintenance, Security, Browse Sites.
The SiteID is 4 digits - e.g. 9999
You'll also need to know the number of Years that are to be retained, which includes the current Academic Year. Normally this would be 5 or 6 years.
We will supply a Key for the day that you want to run the purge (this is a safety check to make sure it isn't ran accidentally).
The purge is ran via the command prompt in the EXEC\TERMSSQL folder and you should have a complete backup of the database as this deletes data. Also ensure no users are in the system
The command line would be (depending on the parameters) something like
TPURGE SITE=9999 YEARS=6 KEY=79398