hi,

see rrb has released link to check the application status which was was active till 30th September 2020, however  Accordingly the first phase of the Exam is scheduled for 23 lakh candidates approx. to be held from 28.12.2020 to 13.01.2021 in various cities all over the country. - Candidate Helpdesk Login Form link would Available only between 19.12.2020 21 hours 30 minutes to 13.01.2021 23 hours 55 minutes. so since  you have the query to change the category, I suggest you to login and do what takes afterwards.