How to get to Ginza by subway at Oshima Hotel in Tokyo, Japan?

You mean APA Tokyo Oshima Hotel, right?

If so, as shown in the figure, the nearest subway station to this hotel is Zhuji Station of Tokyo Metro (five minutes' walk from the hotel to exit A4 of Zhuji Station).

Then, as shown in the figure, the train from the semi-hidden gate line of Tokyo subway to the central forest arrives in Otmachi;

Then transfer to the train heading for Diwa on the Marunouchi Line of Tokyo Metro and arrive at Ginza Station. The whole journey takes about 20 minutes and costs 195 yen.