UEFI newbie: How to wipe the whole disk?

Hi geeks.

I am a total UEFI n00b, only having one PC with it all others being legacy BIOS systems. I know my way around BIOS and have now familiarized myself with UEFI settings, I think that in settings and how to change them / what they do I do not need help.

My issues are with a clean install wiping the whole disk, and to understand the partitioning. This PC had an OEM German Windows 8.1 which I upgraded to 8.1 Pro, then replaced the German 8.1 Pro with an UK English one simply by clean installing a retail 8.1 Pro on top of the German one, not wiping the disk but the "traditional" way which simply moved the German OS to Windows.old folder which I later removed.

The UK English 8.1 Pro was later upgraded to 10 Pro Build 10240, further to builds 10525, 10532 and finally now to 10547. Now I would like to start from scratch, clean install totally wiping the disk.

Questions:

1. Why three recovery partitions (white highlight in screenshot above). I understand the last one, it's the manufacturer's recovery partition which allows me to restore the original OEM German Windows 8.1. But why the two others?
2. How do I proceed with clean installing Build 10547 wiping the whole disk? I tried it, got to disk tools in setup, removed all other partitions but the dialog didn't let me to delete the partition C: (yellow highlight)
3. Essentially I would like to start from this situation (screenshot from this TF tutorial), whole disk unallocated space, partition it as I want to and install Windows. If this was a BIOS system I could easily do it, the Windows Setup Disk Tools dialog creating the System Reserved automatically when I create the first partition in that unallocated space, but UEFI seemingly lets me to delete all other partitions but not the C:

Any insight greatly appreciated, please help me to understand the UEFI. Please notice that I have recent system images allowing me to restore this functioning system anytime I want to, making experimenting easy.

Kari, a n00b

Did you boot from your install media or run setup.exe from Windows? I've never had an issue deleting any partition when booting from my install thumb drive. I just chose custom install and delete as shown in your last screen shot. Windows then creates all the partitions it needs automatically. I use the same procedure if its UEFI of legacy. The only difference is the partitions Windows creates. Instead of the first partition being called System Reserved its called Recovery in a UEFI install. And you end up with a EFI partition where the Recovery is on a Legacy install. I think that's how it goes, I'd have to fire up my laptop to confirm, I'm on my Legacy desktop PC at the moment.

Kari, as far as wiping the Partitions, are you trying to just remove them or do you want to destroy the data? You can use diskpart and run the clean command, or in the advanced options delete the volume. or you can run 'clean all' command to destroy everything. I know you know how to get to a command prompt in the installation media. But if you will delete all partitions where it says unallocated and in advanced options select new and apply, your UEFI Installation media will create the correct partition structure for you. It should be 4 partitions with Windows 10. Install to the last one.

alphanumeric said:

Did you boot from your install media or run setup.exe from Windows?

Naturally booting from Build 10547 Flash drive and selecting Custom Install.

alphanumeric said:

I've never had an issue deleting any partition when booting from my install thumb drive. I just chose custom install and delete as shown in your last screen shot. Windows then creates all the partitions it needs automatically. I use the same procedure if its UEFI of legacy. The only difference is the partitions Windows creates. Instead of the first partition being called System Reserved its called Recovery in a UEFI install. And you end up with a EFI partition where the Recovery is on a Legacy install. I think that's how it goes, I'd have to fire up my laptop to confirm, I'm on my Legacy desktop PC at the moment.

That's how I have understood it. However, been trying this now four five times, I always get to the point where I have deleted all other partitions but when there are only unallocated space and C: partition left, selecting the C: grays out (disables) the Delete option.

essenbe said:

Kari, as far as wiping the Partitions, are you trying to just remove them or do you want to destroy the data? You can use diskpart and run the clean command, or in the advanced options delete the volume. I know you know how to get to a command prompt in the installation media. But if you will delete all partitions where it says unallocated and in advanced options select new and apply, your UEFI Installation media will create the correct partition structure for you. It should be 4 partitions with Windows 10. Install to the last one.

Deleting the C: partition with Windows Setup Disk Tools is not possible, see my previous post.

I will give the DISKPART a go, cannot understand why I hadn't thought of that!

Kari said:

Naturally booting from Build 10547 Flash drive and selecting Custom Install.


That's how I have understood it. However, been trying this now four five times, I always get to the point where I have deleted all other partitions but when there are only unallocated space and C: partition left, selecting the C: grays out (disables) the Delete option.

OK, that's weird then?

yes, that's a new one on me.

Kari said:

Naturally booting from Build 10547 Flash drive and selecting Custom Install.

That's how I have understood it. However, been trying this now four five times, I always get to the point where I have deleted all other partitions but when there are only unallocated space and C: partition left, selecting the C: grays out (disables) the Delete option.

Make sure you disabled Secure Boot.
Secure Boot - Enable or Disable in UEFI

I don't think fast boot (essentially hibernation) would cause this since you're booting from the USB, but turn that off too just in case.

Make sure you're doing a cold boot.

That's all I can think of.

Bill

edit: if you post a diskpart of your drive selecting the parsons and showing details, it would be easy to identify the Recovery parts.
diskpart
sel dis 0
lis par

Select each partition (1-7)
sel par #

Show details
det par

exit

OEMs set up the drive differently.

The first Recovery part is probably WinRE, the 450 MB part might have been created when your tried to install, and the 3rd Recovery part - you identified as the OEM Recovery.