you need to boot to a different OS to blow off windows completely
When you finally boot into Linux you will come to a point where you will partition your HD. Just opt to have the win partition removed.
I do not believe your problem is HD or partition related. You are having a problem creating a RAMdisk; this is a pseudo disk in RAM. this is used during boot as there are no partitions mounted and the kernel needs to be decompressed into the RAMdisk before you can finish booting.
Get that problem fixed and then worry about removing the partition later. if you insist on removing the win part first you might be able to with teh win install CD.