Drops an existing stream.
If the DELETE TOPIC clause is present, the stream's source topic is
marked for deletion. If the topic format is
corresponding schema is deleted. Topic deletion is asynchronous, and actual
removal from brokers may take some time to complete.
DELETE TOPIC will not necessarily work if your Kafka cluster is
configured to create topics automatically with
auto.create.topics.enable=true. We recommended checking after a few
minutes to ensure that the topic was deleted.
If the IF EXISTS clause is present, the statement doesn't fail if the stream doesn't exist.