we are family of 4, we want to go to big Buddha in lantau island, can we take bus from regal kowloon

There is no direct bus, so you are suggested to take the MTR and cable car. From the hotel, you can walk to East Tsim Sha Tsui Station to take the West Rail Line to Nam Cheong Station, and then change to Tung Chung Line to Tung Chung Station. Then walk to take the cable car to the Buddha.