can i refund the deposit of my octopus card HK$50 at the airport Hongkong?

If i have to refund it at airport express station, can i reach that by walking from the check in counter (T2) ? because i go from harbour hotel mongkok by taxi straight to the airport with 3 big luggages, so it is hard for me if i must stop by at the mtr station.
please help. Thank you