I want to change email by removing names of those who have received it. Why will this not work?

I am trying to forward e-mail but do not want to keep all the e-mail addresses for persons who have already had the e-mail. When I remove them, the rest of the e-mail is deleted as well

Well, Wanda----you can't alter the original email----BUT ----if you click on forward first---you will be able to edit the copy before it's sent.
Soooo--Click on forward----then highlight those previous addresses and press the delete key on your KEYBOARD, and they're gone in a flash.

With Yahoo----sometimes you won't see anything in the forward window---in which case you have to click on the down arrow next to the forward tab and choose "as inline text". That puts the copy in that window where you can edit to your hearts desire.

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Yahoo---as they like to do---are making waves again, and on some accounts, have removed that down arrow. If that has happened to you and you see nothing in the forward window----do this>>>>>click on "reply" instead of forward, and you will see the message with previous addresses. Delete them as described above----but before sending, you will now have to change the TO line, by putting in your own recipients.
Just a minor "back door" approach, but in the end, works just as well.