Answer
To sell IPO shares in Zerodha, log in to Kite, go to Portfolio -> Holdings, select the allotted stock, and click ‘Exit’ to place a CNC sell order.
Orders can be placed during the pre-open window (9:00 AM – 9:45 AM), but there is a freeze period from 9:45 AM to 9:59 AM. Regular trading starts at 10 AM.