A family of Microsoft word processing software products for creating web, email, and print documents.
It really depends on whether the diacritical marks are part of the actual characters, or are the separate diacritical marks that can be used. If it's the former, you need to do it on a character-by-character basis for each diacritical mark applicable to that character. For the latter, you could use Find/Replace to delete just the diacritical marks.