Use subject factory to create subject for deletion rather than using the string/

Change-Id: Ib7680b07642d676e9ad7f10fd59471880aa79771
diff --git a/web/api/src/main/java/org/onosproject/rest/resources/NetworkConfigWebResource.java b/web/api/src/main/java/org/onosproject/rest/resources/NetworkConfigWebResource.java
index 3afeb3a..39c9dd3 100644
--- a/web/api/src/main/java/org/onosproject/rest/resources/NetworkConfigWebResource.java
+++ b/web/api/src/main/java/org/onosproject/rest/resources/NetworkConfigWebResource.java
@@ -362,7 +362,7 @@
     public Response delete(@PathParam("subjectClassKey") String subjectClassKey,
                            @PathParam("subjectKey") String subjectKey) {
         NetworkConfigService service = get(NetworkConfigService.class);
-        service.removeConfig(subjectKey);
+        service.removeConfig(service.getSubjectFactory(subjectClassKey).createSubject(subjectKey));
         return Response.noContent().build();
     }