When you upload a WSDL to WSO2 Governance Registry it will create a Service Artifact automatically for that WSDL. But in case you do not want that to be automated and need to add services differently this is how to disable that feature.

1) Open GREG_HOME/repository/conf/registry.xml

2) Search for 

<property name="createService">false</property>

and uncomment them.

There will be two locations generally for normal WSDL handler and for ZIP or archive based upload handler (Where you upload multiple WSDL files together).

Save registry.xml and restart your server. Now you can observe that it will not create Services automatically for WSDL uploads.