'your access token',
'refresh_token' => 'your refresh token');
$wrap = new CS_REST_Lists('List ID', $auth);
$result = $wrap->delete_custom_field('Custom field key');
echo "Result of DELETE /api/v3.1/lists/{ID}/{Key}\n
";
if($result->was_successful()) {
echo "Deleted with code\n
".$result->http_status_code;
} else {
echo 'Failed with code '.$result->http_status_code."\n
";
var_dump($result->response);
echo '';
}