Masking / Removing a portion of url in user browser in F5 APM

The issue here is that browsers don't really work that way. What is displayed in the address bar is what they're going to ask for, and to change or hide that is usually not a simple task. You could, as Arnaud suggests, write some complex code to push the URL into browser side JavaScript (and possibly cookies) and then try to make the browser doing everything asynchronously (ie. Ajax), but then you're literally rewriting the application. In fact this is exactly what Ajax (client side asynchronous JavaScript) achieves.

But even if you did that, you're not really providing any real security. The client still has to make these requests and a clever user can still see exactly what's going on. Most application devs these day, long after the Ajax hype has passed, have realized that a RESTful, transparent experience is usually the best way to go.