What is Interior Designing? if i have knowledge of 3d studio max and vray rendering,it's enough to be a Architectural/Interior Designer?

Of course not. to work in a field you have to cover required: Knowledge, Skills and experience for the same specialty.

now you are talking about1 tool skills. for example knowing interior design require studying ergonomic science. it is not about going to college it is about absorbing required knowledge and skills.

No, it's not enough just to have some knowledge in the programs. If you want to work with architecture - you have to be able to read the drawings and know technical and ergonomic requirements to the architecture and interior, also you need to have a good knowledge in different styles and color matching and a lot more. 

Need knowledge about material and skilled people available for the work.

Need very good bargain and interpersonal skill.

Knowledge of traditions and life style of client.

Contract legal knowledge many a things are there.

Once you start you can learn it may be a steep learning curve.

Keep in mind never afraid of people good people will give give you memories and bad one experience.

you can master the tools, but you need to become a master at listening. Architecture and interior design are responses to specific problems. You should learn to manipulate empty space and render it livable. They are many ways to order space with each offering a different kind of mood, atmosphere, energy and each should respond to a need. Learn colorimetry, how to divide a space with light and matter. Start by looking at how Greeks built their temples and how they mastered visual illusion to make appear different then they are without adding costly materials. Learn modern architecture to find out how living space get integrated into our daily life. Read as much as you can magazines on interior design, go to the museum, you will never stop learning, and enhance your vision on things of life.