delete linux partitions

["Abbas Asif" <abbasasif@xxxxxxxxxxxxxxx>]

hi
i wanted to delete my linux partitions as i want to throughly dedicate my 1 HDD to windows and the other HDD to linux.so booted through a bootable red hat 6.2 cd and run disk druid.it deleted all of them and saved the changes to partition table.but when again i run disk druid it is again showing those partitions.Someone told me to use linux fdisk,i run linux cd in rescue mode and tried fdisk but it is not able to delete it.
i write the following at bash and get the output:
bash# fdisk -l /dev/hda
unable to open /dev/hda

bash# fdisk -d /dev/hda
invalid option --d.

please tell me what should i do.
disk druid is showing the following output
/dev/hda1 win 95FAT 32
/dev/hda5 linux native
/dev/hda6 linux native
/dev/hda7 linux native

Do tell me how can i successfully delete these partitions.
when i run windows fdisk it shows one pri-dos partition and the other ext-dos partition.
help me.
Abbas
JUST DO IT!
IT's NOT A SLOGAN...
IT's A CONSCIENCE.