To close a presentation , perform the following steps:
step-1: click at the File menu.
step-2: click the close option.
step-3: If the current File is unsaved, powerpoint will display a dialog box asking you to choose whether or not to save your file . you can choose to whether or not to save your file. you can choose to click the yes and No buttons.
step-4: select Yes if you want to save the file ,No if you do not want to save the file . you can choose cancel to return to your file without saving it.