Deleting Data permanently

From: Gopi (gopigopi_at_hotmail.com)
Date: 11/01/05 

Date: Tue, 1 Nov 2005 10:17:37 +0300

Hi

We have lot of drive in leased servers, we like to delete permanently
(unrecoverable mode) our data before return to the company.

All are NTFS format drive. is there any tools available?

Thanks
Gopi