deleting partition created by linux

hi all
i have installed red hat linux 6.0 on 8.4gb HDD having linux as only operating system.Now i want to remove linux and install windows NT on it.i boot to this machine using fdisk it displays me partition information as ext2 file system as onlypartition but fdisk doesn’t allows me to delete it. is there is any way through which i could delete the partition listing MBR.i tried fdisk /mbr to fix the problem but in vain.
help me F1