Dban and installing windows 10

Just to clarify, I assume your hard drive is C. Is the D drive an optical drive? As stated, the Windows 10 install disk walks you through the process step by step. Just delete each partition on the list, which will eventually give you the whole disk capacity as unallocated space. Then click New to create a new partition, verify when it shows you the size of the partition, and it'll set about the installation. I prefer to do this job without an internet connection, refuse when it prompts me to connect to a network, and I can then use a local account rather than a MS one. If you have the latter, the internet connection may be desirable.

Is the D drive a second hard drive, then, or what is it? Just looked at my own Windows 10 installation with Disk Management, and I have a C drive, which is the single hard drive, and a separate 500 Mb recovery partition, which doesn't have a drive letter. Windows will create that during the installation process, although it's apparently not big enough for some recent updates, causing them to fail. It's allocated the letter D to my optical drive, which fewer people have these days, but my PC dates from 2008. I find the optical drive extremely useful. Just puzzled about the nature of your drive with the letter D. I can't recall installing Windows 10 on a computer with a second hard drive, but I assume you would be given the opportunity to choose where to install it.

The C is the primary partition.

In the installer, it will ask you which drive you want to install on.

1. Back up important data on both C and D drives.
2. Boot from Windows 10 installation media.
3. Select the C drive for installation, and optionally, leave the D drive untouched.
4. Proceed with the installation process.
5. Reinstalling Windows 10 will restore it to a clean state, but not necessarily the original factory state. If you want the factory state, use manufacturer-provided recovery options. Using DBAN will wipe all data, requiring a fresh Windows 10 installation afterward.