Can i short a stock in CNC?

Can i short a stock in CNC? or i can do it only in intraday?

You cannot short using CNC to take an entry position. You can do this only using intraday product types - MIS, BO and CO.
You can sell using CNC only if you already have holdings in that stock or if have bought the position using CNC on that day.

CNC trades are not auto squared off. So if you were allowed to sell using CNC for intraday and if you didn’t square off that position on the same day, then your shares will be short-delivered and you will face an auction penalty. Hence, not allowed.