Hi would like to ask what is the fastest and cheapest ride going back to Hong Kong Airport?

Well, generally speaking, you need to arrive at the airport 2 hours in advance before the departure. And according to your requirements, you can take bus no.N21 at Tsim Sha Tsui Police Station, Nathan Road and get to the Passenger Terminal Building directly. It takes around 75 mins. And it costs 23 HKD per person.