Find "Access Point Names"
Press the menu icon.
Press Settings.
Press More....
Press Mobile networks.
Press Access Point Names.
Delete data connection
Press the required data connection.
Press the Menu key.
Press Delete APN.
Press the Home key to return to standby mode.
Find "Settings"
Press the menu icon.
Press Email.
Press the Menu key.
Press Settings.
Delete email account
Press the required email account.
Press Remove account.
Press OK to confirm.
Exit
Press the Home key to return to standby mode.