"Create the Hive Metastore Database Tables" ==> Create Hive metastore tables in the backing database (here is Oracle)
"Update Hive Metastore NameNodes" ==> Upgrade the exsiting Hive Metastore tables after Hive itself has been upgraded. You don't need this because there weren't any existing tables in Oracle before you switched.
After "Create the Hive Metastore Database Tables", you should be able to start your Hive service and start to use it. Problem is that the data used to be in PostgreSQL are not transferred to Oracle, and thus you lose all the databases and tables defined in Hive. Please let me know if this is a problem for you.