Remove fields from Media upload box

I want to remove some fields from the media upload thickbox which I am using in the theme options page. I’m trying the following code, it removes the fields successfully however it removes from the thickbox used in the posts as well.
So I want to remove fields only in the thickbox being used on the theme options page. CAn someone tell me how I can do that? Thanks.

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'] );

    return $form_fields;
}