You can't get rid of the stock browser, but I think you're asking the wrong question. Rather than uninstalling the stock browser, did you want to have Dolphin Browser show up at the bottom, on one of the main 4 icons?
If that's the case, go to the App Tray, then Menu, View Type, Customizable Grid, and you can drag the Dolphin Browser app icon to where the stock Web icon is to replace it.