Well, before I would have answered with a "NO", but after some thoughts I think they can do it, very easy.
Those bankers who don't understand Bitcoin & cryptocurrencies or who understand this movement but realised it is a thread for their companies can easily destroy Bitcoin but with some costs of course.
Or the bankers are the dumbest people alive or they are secretly investing in Bitcoin.
Banks could easily accept Bitcoins and give cash to the people and then hold and destroy/burn all the Bitcoins received. That's so easy to be done by those big Banks in the world.
Of course it was easier last two years because of the low popularity and hype of Bitcoin but also because of the lower number of the cryptocurrency alive.
Now it is almost impossible to destroy the crypto world. People realised we need decentralised systems.
Even if there will be big steps made by big companies trying to destroy a cryptocurrency, another one will be created.
