Remove fields from Media Uploader overlay

functions.php

// edit fields in media upload area
add_filter('attachment_fields_to_edit', 'remove_media_upload_fields', 10000, 2);
function remove_media_upload_fields( $form_fields, $post ) {

    // remove unnecessary fields
    unset( $form_fields['image-size'] );
    unset( $form_fields['post_excerpt'] );
    unset( $form_fields['post_content'] );
    unset( $form_fields['url'] );
    unset( $form_fields['image_url'] );
    unset( $form_fields['align'] );
    unset( $form_fields['image_alt'] );

    return $form_fields;
}

// print_r($formfields); to see what you can add/remove