Each presentation window must be closed individually. If you only have one file open, you can close it and keep PowerPoint.
Click the File Tab.
If you have not saved the presentation since making changes, a dialog box will appear asking if you want to save changes to the presentation. Click Save if you wish to save your changes; click Don’t Save if you do not want to save your changes; click Cancel if you do not want to close the presentation.
The file is closed but PowerPoint is still running. You can still browse for a file to open, create a new presentation, and access PowerPoint’s options.