If I lock my choice in round 6 of JoSAA counselling, will I need to report physically or online? How should I report?

You don’t have to lock your choice in round 6. It is automatically locked. For reporting to any institute you should check the respective institute’s website and for further information. Please don’t come to Quora for anything related to institute related problems. You might get stuck in a big problem. It is best to see on the their respective sites and if it’s not there you can call them or wait.