Partitioning

Hi, FNaFan.

My recommendation would be to:

1) Image the entire disk (along with the data partitions you want to preserve to an external drive) with a reliable imaging program like Macrium Reflect (free) or equivalent.

2) Run the clean install but select "Custom" at the beginning and delete every partition until there is nothing left but unallocated space on the disk for Windows to install on.

3) You'll end up with 3 small partitions at the front of the disk (Recovery, EFI System Partition, and a small MSR - this last won't show in disk management) and a large C: Drive.

4) Then you can shrink the C: drive to make room for and create new data partitions to restore from your image.

FNaFan said:

I want to install Win 10 from scratch. For that I have created a bootable USB and downloaded everything. But I just wanted to confirm about partitioning the partitions. My Previous Win 10 was installed in C:\ and I want to install Win 10 in the same drive, formatting it. I dont know how to do so(Delete, Format or just press next). And will i lose data in other partitions? I have 4 other partitions and dont wanna lose data in them. And while i installing i noticed that there are many other recovery partitions (4 taking up nearly 17 gb) and 1 oem partition (1gb) and 1 EFI System partition 260 mb. So what should i do with these?

This drive also contains information on how to restore the OS to how it was when first purchased; the data being located in one of the 'hidden' partitions. If you ever wanted to go back to your previous Windows OS, then these files would be required unless you used something like Macrium Reflex (free for home use) to take an exact image of all the partitions on your hard disk to another internal or, preferably, external HD.

You also need to make sure that all personal files are backed up so that these can be restored after the clean build of Windows 10.

Creating a separate partition as suggested by Word Man is a good way to store personal data; it keeps it separated from the OS on the C Drive making backup & restore of the OS simpler!

The suggestion/advice to make a backup of the complete hard disk means that the OEM Partition will be saved in that backup.

First read this tutorial: Clean Install Windows 10 Directly without having to Upgrade First to fully understand what is required. During the Upgrade form Windows 7/8 to Windows 10, Microsoft will 'register the OS to your specific PC/Laptop such that any subsequent Clean Build will automatically get registered. By performing a clean install without doing an upgrade, you have to perform certain functions to 'force' a registration.

The next suggestion was to wipe the HD completely, then install Windows 10 using the method detailed in the above tutorial.

The last step was to shrink the size of the C Drive to allow a new partition to be created to store your data.

WightWalker said:

...
First read this tutorial: Clean Install Windows 10 Directly without having to Upgrade First to fully understand what is required. During the Upgrade form Windows 7/8 to Windows 10, Microsoft will 'register the OS to your specific PC/Laptop such that any subsequent Clean Build will automatically get registered. By performing a clean install without doing an upgrade, you have to perform certain functions to 'force' a registration....

Doesn't pertain in OP's case since they've already done the Win10 upgrade and established a digital entitlement. Even if that weren't the case, the gatherosstate.exe method wouldn't be necessary (although permissible) since buld 10586 and onwards now allows direct entry of a valid qualifying OS product key.