Thanks for your inquiry. Please note that Aspose.Words mimics the behavior of MS Word. You cannot disable copy option using Aspose.Words. This is operating system level setting which is not stored in the document and therefore cannot be controlled by Aspose.Words.
You can use following code example as a workaround. By using ProtectionType.AllowOnlyFormFields, “copy/paste” is disabled by MS Word in document. However, user can enter data in the form fields and content controls in the document.
Document doc = new Document(MyDir + "in.docx");
doc.Save(MyDir + "18.4.docx");