First let me thank you Mr.Hanky for your immediate response.
I've to submit the free space which i'm going to get by dropping that unused schema , to my manager. He want to know the statistics of each schema. Though it is unsued, but we have all the data of the finished projects in that schema. So, i've to know the size and inform him by today evening.

Sorry to say this , but , The two methods which you told cannot be done here. B'coz its on our prod box. Is there any other way round?

Thanks again