You can configure the ESB to use a remotely hosted WSO2 Governance Registry instance as the metadata and configuration store, instead of using the embedded registry instance. For that you need to edit the ESB_HOME/repository/conf/registry.xml file and modify the database configuration to point to the same database as the remote registry instance. Edit the dbconfig element in the registry.xml and make sure that the ESB is pointed to the same database as your WSO2 Governance Registry instance.
For more information see Registry.