No the Banks cannot make Bitcoin disappear. Bitcoin is a currency made by the people and for the people there isn't a way to just make it disappear.
I agree with you it is really not going to happen that bitcoin is going to disappear the banks. As bank is one of the biggest contributor of tax in a country and the government is not going to allow that banks are going to be disappear because bitcoin is not going to contribute in the tax of a government. So it is not going to happen.