Getting rid of Noto Sans Symbols and other fonts in Powerpoint

If someone worked on your PowerPoint presentation using Google presentations, you can end up in a situation that PowerPoint gives an error when saving the presentation that the a font (like Noto Sans Symbols) cannot be found.

Getting rid of this is not easy. Find and replace fonts often does not solve the problem for me.

Solution that did work: 

1. save the Powerpoint as an XML file
2. Open in a plain text editor (Notepad++, ...)
   
3. find an replace "Noto Sans Symbols" (or the font mentioned in the error when saving) with something like "Arial"
4. save again
5. Open the XML file with PowerPoint
6. Save again as .pptx
7. phew!

I found the solution here...