Hello... You will need to Delete the Partitions on it... and will have to done outside of Windows or with a basic Boot disk... Windows files on the Orig hardrive will not let you delete them while in Windows.
1) BOOT any Windows Install Disk, you can navigate to delete the Partitions... "custom install"
2) Have Windows format a USB stick Fat32 and check the option "make bootable"
Boot the USB Stick and use DOS command FDISK to delete all the Partitions.
Once partitions are deleted... use Windows "Disk management" to create a new Partition and format... and make it Active.