Hi Saify,
I think there's a conceptual issue here that may help make it clearer.
Your question is about "creating" a topic, but that's the wrong way to think about it. A better way to think about it is that topics don't really exist: a topic is more like a tag that is associated with the message.
As a client, you can subscribe to a topic that doesn't exist. There's no need to publish to it first, or do anything else to "create" it. Likewise, there's no way to "delete" a topic, because they don't exist in a persistent way.
If you think of it like a tag, you can imagine the transactions between the clients and a broker being something like this:
Subscribe: client says to broker "please tell me about any messages you receive that are tagged with 'my/topic/here'".
Publish: client says to broker "here's a message which has the tag 'my/topic/here'".
There are complications to this of course (retained messages, etc) but fundamentally it becomes clearer if you don't think of a topic as being a thing that exists, or has to be created or deleted.
Jon