dropping a PUBLIC rollback seg

I have a group of users who are new ORACLE on the VAX as well as new DBAs. We are running ORACLE for VAX/VMS 6.0.36 (6.2). What the user wants to do is to DROP a public rollback segment that is current in use, as well as the tablespace that contains the rollback segment. He has tried the DROP PUBLIC ROLLBACK SEGMENT and DROP TABLESPACE and both commands returned the Rollback segment in use error. Is there a way to drop these rollback segments so he can drop or take the tablespaces off line?

Thanks,

-- 
Mike Jacobi
NAVSSES VAXCluster system manager
System_at_Eagle.Navsses.Navy.Mil
System_at_Condor.Navsses.Navy.Mil

Disclaimer - I speak for myself.  No-one else.