Yes, you can convert an open normal order into a stop-loss order by following these steps: 

Step 1: Visit the ‘Order Book’ by tapping on the Orders tab in the bottom navigation bar.

Step 2:  Click on the order you wish to modify.

Step 3: Tap on the ‘Modify Order’ button.

Step 4: This will reopen the order entry screen for you to make changes.

Step 5: Select the ‘SL Lmt’ or ‘SL Mkt’ option under Order Type and enter the trigger price at which you want the order to be triggered.

Step 6: Review and submit the modification request.

Similarly, stop-loss orders can also be modified to a normal order by selecting the Market or Limit option under Order Type on the modification page.