[smark]

To remove the grill, On the 451, you have to remove the front bump fender Assembly. You probably have to do the same thing, on your 453 model.

Bumper & Components - Front for 2017 Smart Fortwo | MB Online Parts

www.mbonlineparts.com

Grille & Components for 2017 Smart Fortwo | MB Online Parts

www.mbonlineparts.com

 

[smark]

It looks like a push pin or plastic rivet as mentioned in post #3. Obtain a fork shaped tool and you should be able to pry the rivet out for removal.

I owned this snap on trim remove tool for over 45 years now. You can buy Harbor freight plastic ones really cheap too.