Hi Abhinav,
You can deactivate the IBAN from the Product which is assigned to your IHC accounts (BCAs).
In-House Cash uses SAP functionality which was originally designed for bank account management which means there is a lot of irrelevant functionality when using IHC to manage company subsidiaries and such like. Think of it like this, if you open a new bank account with Citibank/HSBC - they will generate a new account number and IBAN for your account, this is what the BCA IBAN is, but it isn't required for IHC.
Hope this helps,
Jack