How to remove Language neutral as an option programmatically and as a setting
This is how you can remove Language neutral as an option programmatically. Put the code snippet in your module.
<?php
function mymodule_form_alter(&$form, $form_state, $form_id) {
if ($form_id == 'node_type_form') {
unset($form['language']['#options']['']);
}
}
?>
If you want to remove the option on a content type just mark Require language (Do not allow Language Neutral) in the edit view of content type in the fieldset Multilingual options