Purge older v$xml_audit_trail records

How do I purge (older) records from v$xml_audit_trail records? We regularly remove the associated XML files from the OS but the view still has millions of records:

select count(*) from v$xml_audit_trail;

2,917,998

SQL> show parameter audit_trail

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

audit_trail                          string      XML, EXTENDED

SQL> show parameter audit_file_dest

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

audit_file_dest                      string      /home/oracle/admin/fsprd2/adump

> ls -1 /home/oracle/admin/fsprd2/adump/*.xml | wc -l

8085