Using gloves and a suction cup gently lift the LCD sheet (no more than 90° failing to do so may bend the LCD and cause image displaying issues);

Meticulously clean the inside. Do not use any detergent at most a very lightly humidified microfiber / lint-free cloth ;

Do not use an air spray as those might leave marks. Best to get rid of dust is a simple hair dryer going from the top center to the edges ;

Reassembly is going back those steps making sure to get rid of your finger-prints ;