can not delete option group.

Hi,
I am trying to delete option group but I get following an error message.
Fatal error: Cannot delete option group linked to products. in ~/includes/controllers/ctrl_option_group.inc.php on line 228

Plase give me advice to solve this problem.

You cannot delete an option while it is linked to products. Go to the products using the option and unset it. Then you may delete the option value or group.