Remove the message in my e-mail

Hello,

I am using free avast, and since several days or weeks, Avast adds a message “This computer is protected by Avast” or something like that in every e-mail I send.
I want to remove it. Even disabling the e-mail protection doesn’t prevent Avast to put this message in all my e-mails ?! So Avast says he is protecting my e-mails even if the protection is desactived, I can send virus and Avast would say “Everything is ok, Avast is protecting this computer…” xD

I don’t send virus, but I don’t want this message in all my e-mails.

Thanks to tell me how to remove it.

Edit : just saw the topic about it -.-

Please (re)search before posting.
The answer has been already given many times and there is even a sticky for it in this forum.
https://forum.avast.com/index.php?topic=180216.0