Hi Mary,
I assume you are referring to an email message to one of the radiant email groups?

It depends on your email program, so I'm just going to give general instructions.

First, click "Reply" or whatever you normally do to reply to an email message.
So, you will then have an email in some sort of window where you would normally write your message.

Scroll down, and you will see the previous post that you are replying to. Use your mouse to highlight the part you don't want to keep, and then hit the delete key on your keyboard.

Give it a try and let me know if it works or if there's some other issue.

Kitty