See your brother won't able to withdraw money from the bank till you give a no objection certificate to your brother he has a succession certificate in both cases your consent is required.
The bank follow procedure of indemnity bond and no objection certificate from all legal heirs to disburse fund in name of the nominee for legal heirs.
Please refer the below link rbi has made it clear so he will require a Succession certificate or a noc from you.
https://m.rbi.org.in//scripts/NotificationUser.aspx?Id=2284&Mode=0