opt for slide you want to save as an image.
If you want to convert all the slides to images, select any slide.
SelectFile>Save As.

In PowerPoint for Mac, selectFile>Export.
Choose the location where you want to save the file and enter a name for the image file.
Select theSave as typedown arrow to display a list of file formats.

By default, PowerPoint Presentation (*.pptx) appears in the text box.
On Mac, use the menu next to File Format.
snag the image format you wish to stash your presentation.
Choose either GIF, JPEG, PNG, TIFF, BMP, or WMF.
In PowerPoint for Mac, choose eitherSave Every SlideorSave Current Slide Only, then selectExport.
Choose whether you want to exportAll SlidesorJust This One.
The slide is saved in the selected file format.
This new folder uses the same name as the presentation.
To save a slide as an image in PowerPoint Online, selectFile>Download As>Download as Images.
The image files are saved in aZIPfile that is downloaded to your rig.