A Power Point presentation can be openly licensed if you own the copyrights to all content of the presentation or have obtained the rights to distribute and openly license all materials used (e.g. images, text, graphics).
However, Microsoft assets (e.g. images, icons, pictograms, shapes, animations, smart art) that are included in PowerPoint must be excluded from the open license.
The reason for this is that Microsoft’s terms of use only permit the use of this creative content (such as icons, images, graphics) within Microsoft 365 applications and in the files exported from them (e.g. PowerPoint presentations, PDF export) for sharing or publication.
An open license (e.g. Creative Commons) refers to the entire work and would also allow third parties to reuse the Microsoft assets it contains as they wish. However, this is not permitted because Microsoft expressly prohibits this further use outside the Microsoft environment and outside the original file:
“Use of program elements such as images, icons, animation elements etc. outside the program is generally not permitted. Please refer to the respective terms of use and license conditions for your software.”
You may therefore openly license the presentation as a whole, but you must make it clear that all Microsoft-owned content (e.g. symbols, images, design elements from PowerPoint) is not covered by the open license and may not be used separately:
“The presentation is licensed under the [selected open license, e.g. CC BY 4.0], except for all images, icons and design elements contained in Microsoft PowerPoint. Microsoft’s terms of use apply to these.”