Comments screen in backend, how to disable email address of commenter for non admins

There is a filter 'comment_email'. Hook into that filter after the action 'load-edit-comments.php' and hide the email:

add_action( 'load-edit-comments.php', 't5_hide_commenter_email' );

function t5_hide_commenter_email()
{
    if ( ! current_user_can( 'manage_options' ) )
        add_filter( 'comment_email', '__return_false' );
}