Do you need to use DBMS_AUDIT_MGMT to clear out Audit Logs, or can I simply purge them?

Auditing was not configured properly the last time that our database was moved to a new server. I'm concerned about doing anything that is going to create a lot of redo, because we have approx. 90 GB of audit logs. So if DBMS _AUDIT_MGMT generates redo, it's going to probably take several weeks at minimum to fix this problem without blowing out my archive logs. This is a little over two years of data. Also, our audit logs are being stored in the system tablespace, so if it does take several weeks to clean out, we