There is no way to disable the back button reliably. Every method, short of writing your own browser, can be easily disabled. This question has been asked millions of times, for years and years. The "back" button is integral to how browsers work, and is firmly a part of the user interface and the collective "user expectation". Trying to fight it is usually a sign of poor understanding of the web, a flawed application model , and/or bad design!

Users will press the "back" button. They will be irritated if it doesn't work. They will often simply close the browser completely if your application doesn't behave as they expect.