Hi,
I want to turn off underline variable. However, there's some issue with the below command in my environment.
SET underline OFF;
Please refer to the below screen shot to see the issue.

The database is 11.2.0.1.0. I am executing the command in SQL Developer 4.0.3.16.
Could you please let me know how to resolve the issue?
Thanks and regards,
Manoj.