Exam form filled for both groups, but want to attempt only 2nd group

No impact in Result.

No issue,Concentrate on 2nd gr.from right now.

ICAI had opened Correction window in https://icaiexam.icai.org/ for changing the group till 15th September. Currently it is unavailable. So concentrate on the group which you want to clear. In your marks sheet, "Absent" will be remarked against the relevant subjects.