How to "mark" a section of text in a Word document, so that it can be easily deleted using Interop.Word

Question

I have a Word document that is used both for emailing and digital signing. When used for digital signing, a section of text in the document should be removed.

How (in Word) do I "mark" this section - without it being visible when the document is emailed - so that I can find it and delete it, using Microsoft.Office.Interop.Word?

Thanks, guys.