@aspears,
Thanks for your inquiry. You can find the desired text in the document and replace it with new text. Please read the following article. Hope this helps you.
Find and Repalce
Please check the following code example. Hope this helps you.
Document doc = new Document(MyDir + "Before.docx");
String findText = @"Fermentum gravida dolor diam gravida aliquet ad leo a natoque vel a ridiculus erat sociis senectus arcu accumsan primis mus a. Facilisis vestibulum nunc a in dui a non dui a proin consectetur diam diam placerat. Egestas curae a etiam taciti consectetur habitasse nec a id at vestibulum morbi dapibus orci etiam scelerisque ante vestibulum vivamus dui turpis. Adipiscing hac habitant parturient conubia quisque augue in a a proin adipiscing malesuada praesent placerat dignissim scelerisque hac a hendrerit viverra semper.";
int replace = doc.Range.Replace(findText, "Paragraph Removed.", new FindReplaceOptions());
doc.Save(MyDir + "17.8.docx");
.