Extract code snippets from how-to-delete-all-the-comments-by-an-author-from-all-the-slides-in-a-presentatio.md

Extract the code snippets from [docs/presentation/how-to-delete-all-the-comments-by-an-author-from-all-the-slides-in-a-presentatio.md](https://github.com/OfficeDev/open-xml-docs/blob/main/docs/presentation/how-to-delete-all-the-comments-by-an-author-from-all-the-slides-in-a-presentatio.md) and use docfx snippets to retrieve them from the samples folder and audit the text.