Hi Marco,
I wil help you
Look at the front of the grille. You will notice some screws. These are easy to remove. The problem is the fixing around the headlights. It's done with clips and with a tight fit.
I removed the grille in this way: i took off the bonnet en stuck a screwdriver between the grille and the upper chassis bar. I made sure not to damage the bar by winding a piece of cloth around the screwdriver.
Be very carefull and use limited force, for the components can easely break.
Good luck,
Mike