The clipboard, and any application you paste into, then follows its own settings and access controls. The website cannot remove a copy after you paste it into another application.
The downloaded file is a plain-text file on your device. The website cannot remove a copy after you share the downloaded file. Review the full brief before exporting it, particularly on a shared device.
Device backups and any destination application follow their own settings and access controls. The page labels the output not sent, but it cannot see where a copy travels afterwards.
If you need to clear the working form, use the reset control and confirm the output is empty. That removes the page’s draft; it does not erase an earlier clipboard entry, a downloaded file or copies held elsewhere.