In the ‘olden days’ when we used floppies to install our o/s we were given the option to
‘F-Disk’, thus enabling you to clean off everything on the h/drive.
No FDisk was to prepare a new drive with an active partition and to split the drive, if needed. The format command from dos wiped the drive.
If you use XP or Vista you can use the same from the installation disk to delete the partitions and recreate partitions. After his is done you can then format the drive prior to installing the operating system.
It would be usefull to know if this is a branded computer, ie restore disk and hich operating system you use.