It may be necessary to clear your user setting and return to the default options. This can be effective for removing the auto-login option.
Usually the settings can easily be cleared by clicking the "Clear Settings" link on the Vitruvius splash screen shown below:
However, if you have enabled auto-login the application will attempt to bypass this screen and you will not be able to click the link. It is possible to disable auto-login from within the application: Disable Auto-Login.
If you are unable to disable auto-login please continue reading.
Navigate to your systems local application data directory. Replace the username portion in the following address with yours to find your local application data directory.
Here you will find a directory named 'The_Vitruvius_Project'. Delete this directory to clear your settings. Do not delete the directory named 'The Vitruvius Project' without the underscores. This will result in the need to reinstall the application.
Once you have deleted this folder all settings will be returned to default the next time the application is opened.