Remove Gutenberg Buttons Block

This added to the functions.php allows the removal of specific Gutenberg blocks.

function hide_default_blocks($allowed_block) {
    $blocks = WP_Block_Type_Registry::get_instance()->get_all_registered();

    unset($blocks['core/buttons']);

    return array_keys($blocks);
}

add_filter('allowed_block_types_all', 'hide_default_blocks');

Part of the issue is that it is core/buttons and not core/button but also the method of removal was incorrect.