"If you have placed the NFO order prior to the end date of the NFO, then you can modify/cancel by following the path Trading > Mutual Fund > Order Book till 1500 hrs on the transaction date.
If you have placed the order on the end date of the NFO, then you can modify/cancel the order before the cut-off time of the NFO. You can view the end date and cut-off time details by following the path Trading > Mutual Fund > NFO/FMP."