Hey Pavit, you can drive to Kinnaur, the distance is around 600kms or you can reach Shimla by bus and then take a cab or a local bus to reach Kinnaur Valley.
Hi,
The most convenient way of travelling to Kinnaur is by the buses that run from Delhi on a daily basis.
Visit this site given below for further details!
https://www.holidify.com/places/kinnaur/how-to-reach.html
Happy traveling!