Information
The Oracle database DBA role is the default database administrator role provided for the allocation of administrative privileges. Unauthorized grantees should not have that role.
Rationale:
Assignment of the DBA role to an ordinary user can provide a great number of unnecessary privileges to that user and open the door to data breaches, integrity violations, and denial-of-service conditions.
Solution
To remediate this setting, execute the following SQL statement, keeping in mind if this is granted in both container and pluggable database, you must connect to both places to revoke.
REVOKE DBA FROM <grantee>;
References:
http://docs.oracle.com/database/121/DBSEG/authorization.htm#DBSEG4414