Its good to hear that you are interested to become a Bank Manager. For this what you can do is to opt for one of the Finance or related subjects in your graduation (preferably).
If you prefer to join a government Bank, then you can attempt to an IBPS exam for Probationary officers or SBI Probationary officers exam. Once you clear one of these you can join the banks as a Probationary officer and with experience you can grow as a Bank Manager. You can join in your Masters like MBA in parallel, while you attempt for these exams just in case it takes time for you to clear the test. https://en.wikipedia.org/wiki/Institute_of_Banking_Personnel_Selection.
If you prefer to join a private sector Banks, you can do so after finishing your graduation and apply for the banks. With further studies, and experience you can settle down as an effective Bank Manager.