Use a pry bar to lift the quarter round from the perimeter of the Pergo flooring. Be careful not to damage the floor where it lies against the baseboard or wall. Set the quarter round aside in a safe place.
Find the last row of planks you installed when you first laid down the Pergo floor. Carefully pry up the first plank from this row.
Lift the plank 1 to 1 1/4 inches. Carefully disengage the plank from the rest of the floor. Set aside each plank as you work. Continue to remove each section of flooring until you get to the damaged area.
Remove the damaged section of Pergo flooring. Install the new section in its place, then replace each section of flooring you removed.