How can i go to hong kong airport terminal 1 from macdonnell road near central?

You can take bus no.A21 at Pottinger Street, Connaught Road Central and arrive at the airport directly. It takes around 50 mins on the way. The ticket fare is 40 HKD per person.

Or you can walk to HK Station and get the Airport Express directly. It costs 100 HKD per person. And the duration is about 25 mins.
You can choose the way you like.