You can short sell shares but have to cover (buy back) before 3:10pm else your broker will buy at any price after 3:15pm. You can't have shorts open for shares for more than one trading session (one day); if you leave the shorts open (like with odin software) you'll be fined 15% at the current market price of the shares on auction day.
this shorting of shares is available through "margin/intraday" account (instead of delivery), in your trading platform. so, choose scrip, qty to short, select sell, and choose "margin" account to do the shorting.