SPRIDEN is the identification table. It contains the user's Banner ID as well as the primary key for person records, typically called the "PIDM". Ideally, the PIDM should never change -- only a user's name or Banner ID should change in SPRIDEN.
To invalidate a SPRIDEN record, set SPRIDEN_CHANGE_IND to 'I'. This will make the record ignored for most purposes. Each PIDM should have only one active SPRIDEN record with a SPRIDEN_CHANGE_IND value of null.