Once you have the bottom and sides of the panel popped off the tabs, you want to to a combination of lifting and pulling along the top edge to remove it from these other types of tabs.
Once the panel is free from these, you can slide it over the door lock knob and pull the whole thing away.
That's it. You now have access to the rest of the door. In order to put the panel back on, just follow these directions in reverse order.