One cannot disable the browser back button functionality only thing that can be done is prevent them.
Below JavaScript code needs to be placed in the head section of the page where you don’t want the user to revisit using the back button:
<script>
function preventBack(){window.history.forward();}
setTimeout("preventBack()", 0);
window.onunload=function(){null};
</script>
Suppose there are two pages Page1.aspx and Page2.aspx and Page1.aspx redirects to Page2.aspx.
Hence to prevent user from visiting Page1.aspx using Back Button you will need to place the above script in the head section of Page1.aspx.
For more reference visit :
Disable Browser Back Button Functionality using JavaScript