I installed similar in our house. A tool came with the speakers to remove the grill. It was a bent piece of wire the same diameter of the holes in the grill.
You could probably make one with a bent paper clip. Friction holds them in and it does not take a lot to pull them out.
Chris & Dianne
Jayco Designer 3110 SOLD 6-11-2016, looking for the next one.
F250 PSD 4x4 Crew Cab