You can use
window.history.forward() on the page. But the thing is to understand what this does.
history.forward() moves the user to the next URL/Page that is in the history. If no URL/Page is there in the history, it simply gives nothing, it will not work.
And disabling the browsers Back button is to mess with browser's functionality.
Going back to the previous page or next page is the default behaviour of any browser. So we can hardly manipuate much of the functionalities. So, I guess we can prevent the back button getting fired by restricting the Url to the very next Url in the History.
Another case is if you want not to store the Url in the history of the page you can use the following bit of code:
Page.Response.Cache.SetCacheability(HttpCacheability.NoCache)
Here we expire the cache from the program, i.e. clear the cache.
Hope you get some idea from this.
Thanks.
:)