Assuming you have a valid Windows install disk, boot from that. You can't change the partition from within a running Windows instance.
Boot from the install disk, delete any and all partitions, install.
I do have a valid windows install disk now, but when i boot it i can't install it says "windows cannot be installed to this disk the selected disk has an mbr partition table on efi systems windows can only be installed to gpt disks"
what option do i choose so i can delete all the partitions so i can move onward and install?