The quoted original is yours to keep or cut, right in the compose window. Reply, Reply All and Forward each bring the thread along by default — usually what your reader wants — and trimming it takes a second.
Select the quoted part and delete it before sending. It is ordinary text in the message body, so it behaves like the rest of your draft — which also means you can cut it down to the one line worth quoting instead of removing all of it.
Two nearby settings do something different, so it is worth knowing which is which:
- Disable quoted text in email view (Settings | Global Settings | Customize Appearance) changes how a received message is displayed, not what you send.
- Sending Headers Style (Settings | Accounts | [select the account]) changes the preamble above the quoted text — see Reply header style — but does not remove the quote.
