Diagnosis
You don't need to remove the entire front panel. The filter is behind a simple, removable grille.
How to Fix It
Power off the unit. Look at the front. There's a rectangular intake grille. Grip it firmly at the top and pull straight towards you. It's held by simple plastic clips. The washable foam filter is right behind it. Rinse it under lukewarm water, let it dry completely, and snap it and the grille back in place.
If That Didn't Work
If the grille won't budge, don't force it. Check for a small tab or indentation at the bottom center you might need to press first. Never use tools to pry it, as the plastic clips break easily.
Heads Up
Clean this filter every two weeks in peak season. A clogged filter is the #1 cause of reduced cooling, strange smells, and the unit freezing up. It also makes the fan work much harder, increasing noise.