is it possible to visit Macau from hong Kong for a day trip. or is it not worthwhile.

Yes, it's possible to have a day trip in this city. There are many ferries operating between HK and Macao.

The Historic Centre of Macao, Camoes Garden and Grotto, St. Domingo's Church and Senado Square gain popularity among local people and tourists all over the world.
So, of course, it's worthwhile to tour. :)