Hold on. I just removed my gmail account from the HTC email earlier today. Unfortunately, I can't duplicate the process because I now have zero accounts on the HTC mail. But I think I remember that you just go to the email program, then "menu" and then "accounts". You should have the ability to delete accounts from that point.
This assumes you are taking an account off of the HTC email app. I suppose if you want to remove the gmail app, you have to remove the whole application.
Message was edited by: unplugged
From home screen hit menu hard key > Applications > Manage Applications > (wait a bit for phone to compute) Scroll down to "gmail" click once then click "clear data" hit back hard key then below it you should see "google apps" click once then hit "clear data" as well. I rebooted my phone and it asked me to re-enter my gmail address and password but not sure if you need to reboot.
Hope this helps.
Message was edited by: BP600
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