I use a flathead screw driver and pry the tabs up. Once they are pried up you can pull that part of the grill outward as the clips will have released. Try the two tabs in the lower corners than you can access from the front first to understand how the clips let go. Then try the others that are a little harder to get at.
i'd say follow GottaBeTRD's reply towards the bottom of the thread. It's the simplest way and less likely to break those clips.
"dont use a Flathead screw driver and push down from the top of the clip. Its much easier if you get a needle point tool like an ice pick or if you have those small screwdrivers those will work. Then go in on the side of the clip you sill see an opening and a small lever you can push down on. just push those down and pull out the same time and it comes right out."