First move the application you want to rename to the top left ‘of the screen in the menu.
Highlight any folder in menu and go to options. 
Now press the power button and choose offline mode. 
As the options menu is still remains opened, now choose rename.

If You have any problem in implementing the procedure on your nokia phone leave a comment here. 

Or

You can also rename it by this trick:

move that folder or icon on top of screen on menu of mobile .
now install any sis or jar apps  in mobile now as installation ends quickly moves to menu and select any folder that can be renamed {but not that one on top now as menu for rename will be open .in background selection area will be on top where that icon exist which was unable to rename .but now can be renamed