Question:
How do I select all database change notifications registered via JDBC driver by my DB user?
Answer:
select * from user_change_notification_regs
Question:
How do I clean all of my DB change notifications?
Answer:
Database change notifications registered via JDBC driver can be deregistered only the same way – using JDBC driver. Therefore you need to execute this code:

This code can be downloaded here.
Comment:
More info about JDBC database change notifications can findĀ in Database JDBC Developer’s Guide