You can delete a role using Oracle Enterprise Manager Database Express (EM Express). Use caution when deleting a role, because EM Express deletes a role even if that role is currently granted to one or more users. Dropping (deleting) a role automatically removes the privileges associated with that role from all users that had been granted the role.
To delete a role:
In EM Express, go to the Roles page, as described in "Viewing Roles".
Select the role you want to delete, and then click Drop Role.
A confirmation page appears.
Click OK.
A confirmation message indicates that the role has been deleted successfully.