I understand your concern. Unfortunately, mistakes made in the application can be a bit serious. And in this case, if the category is not declared properly, then improper declaration of category might affect the eligibility for certain benefits and reservations.

Procedure to Follow:

Contact RRB Authorities:

Reach out Immediately: Just reach out to the concerned RRBs where you have applied and contact them as soon as possible.
Explain the Situation: Explain the error clearly and submit evidentiary documents such as your caste certificate.
Request Correction: Politely request them to rectify the error in your application.
Keep following up with the RRBs .
Prep Supporting Documents:
Caste Certificate: Get a valid caste certificate from the appropriate authorities.
Affidavit: Draft an affidavit stating that there has been an error and requests correction.
Any Other Relevant Document: Collect all other documents which could help you to substantiate your claim.
Consult Lawyer:
If the RRBs are unable to solve the problem then you can contact an administrative lawyer who would guide you legally and help you in further appealing the matter.
Consider the Following:
Time: The sooner you act on this point, the brighter are chances of settling it.
Patience and Persistence: Do not be impatient or lose steam in your follow-up as the correction process takes some time.
Be Honest and Transparent: Explain the situation to the RRB authorities truthfully. Also, provide all documents that may be required.
Explore Other Options: If correcting is proving difficult for you, apply to a few other exams or jobs that do not require a specific category.
It is true mistakes can occur, but then one should act quickly to make the necessary change. After doing this, staying calm makes it quite possible to solve the problem and subsequently gain entry into RRB exams. https://competition.careers360.com/exams/rrb-ntpc