Remove Gmail Account from Thunderbird: If you have any un-used gmail account configured in Mozilla Thunderbird then below mention steps can help you to remove it from Thunderbird. Please follow the mention steps to remove gmail account from Thunderbird.
Open Mozilla Thunderbird
Navigate to Tools -> Account Settings
Then Click on Account Action and select Remove Account
Click on OK button
Now your account has been removed from Mozilla Thunderbird
Also Read: Setup Gmail Account in Mozilla Thunderbird