how i can get to macau from Hong Kong royal plaza hotel?

It is a good idea to visit Macau for one-day. Well, from your hotel, you could take metro or bus to the China Hong Kong City Ferry Terminal, close to Tsim Sha Tsui metro station. Then, take a ferry to arrive in Macau in one hour. Macau is not large so one day is enough for you to see the essence of this city. The famous Macau Attractions(https://www.travelchinaguide.com/attraction/macau/) include the St. Paul's Site, Senado Square, A-Ma Temple Venetian Hotel, Macau Tower, etc. Select these you are interested for visit and return to Hong Kong in the afternoon:)