Can I send a reply without quoting the earlier messages?

Yes. In the actions row under the reply editor, click the "Message history" button to switch between "Full history", which quotes the earlier messages below your reply, and "No history", which sends your reply only. With No history the email contains neither the earlier replies nor the original ticket text, so make sure your reply stands on its own or add an AI summary. The choice applies to the reply you are writing: every new reply starts with Full history. The button is not shown for private notes, since no email is sent.