Removing a Streams Configuration From The Database

Starting from Oracle Database 10g, Oracle provides a means by which you can remove an entire Streams configuration from a database using the DBMS_STREAMS_ADMIN package.
It will remove all the pieces and parts you've configured for the Streams.

Steps:
1- Connect with the Streams Admin user and remove the configuration from all databases involved in the Streams replication configuration

SQL> connect strmadmin/strmadmin
SQL> execute DBMS_STREAMS_ADM.REMOVE_STREAMS_CONFIGURATION();

2- Connect with SYSDBA user and remove the Streams Admin user
SQL> connect / as sysdba
SQL> drop user strmadmin cascade;