GLC, is correct with his suggestion of using delpart.exe which was a utility in the Resource kit that came with the early version of NT. It deletes NT partitions that fdisk which served earlier OS's quite well but has problems deleting NTFS. There is a MS Knowledgebase article to this effect, but as I am at work I don't have the page link to send ya.
Link originally posted by GLC, to me in another thread.
http://www.russelltexas.com/delpart.htm