Usually you WANT this to happen, y'know, so you can take care of the forum problems. XP
But if you don't, open up
includes/config.php and change the line:
PHP Code:
$config['Database']['technicalemail'] = 'your@email.here';
to not have your e-mail address.
Better yet, get an e-mail account solely for the error e-mails and put it in there.
OR, you can go the easy route, open your AdminCP, go to vBulletin Options, scroll down and click "Error handling & Logging", and it'll be under "Disable Database Error Email Sending".