In my opinion, Windows 10 is one of the easiest versions of Windows yet to install. This is especially true with regard to licensing. 99% of the time, if you have run Windows 10 on the PC prior to wipe you shouldn’t even need a license key. Once it syncs up to Microsoft’s servers it should verify the PC is already set. That said there are a few things you can do during install to make your life easier and your PC run as it should.
If possible, Before you wipe ANYTHING, download and run the Media Creation Tool from https://www.microsoft.com/en-us/software-download/windows10
This will prepare a USB stick (or DVD if you have to) that you boot from to install Windows. It is also a good thing to keep in a drawer should you need to repair Windows later. When prompted for 64/32 bit, if you don’t know you need 32-bit you probably don’t.
UEFI vs Legacy boot
Most PCs made/built in the last several years should hopefully default boot in UEFI mode. Which one you choose when booting the install media will affect how Windows 10 partitions your hard drive.
Boot UEFI = GPT partition (more robust, higher partition size/number limits)
Legacy = MBR partition (2TB partition limit, less resilient against file corruption)
https://en.wikipedia.org/wiki/GUID_Partition_Table if you want more details
If you have previously run Windows on the PC, in most cases you can safely select “I don’t have a product key” when prompted to Activate Windows. Upon connecting to the Internet the installer will verify that the PC is already licensed. It is best to be network connected on first boot so it is licensed out of the box to avoid possible activation issues later.
Where do you want to install Windows?
You will be given a list of partitions on all detected drives (not counting the boot media). I HIGHLY recommending not having any secondary drives connected at this point to avoid accidentally choosing or formatting the wrong drive. Do NOT just choose the primary partition as the installer may try to reuse the current partitioning. This can inherit any number of issues you are trying to overwrite from the previous install, and sometimes results in redundant useless partitions. Select and delete each partition on the target drive until you have only one choice named “Drive 0 Unallocated Space”. The installer will take care of all the partitioning from there.
Tricking Windows 10 into creating a LOCAL account.
Microsoft is pushing harder every year for people to setup an account with them for logging into Windows. Understandable, they want you in their ecosystem. With the latest build of Windows 10, you are no longer given the choice of setting up a local login UNLESS you have no network connection when it asks to set it up. For this reason I recommend using a wired rather than wireless to make the following easier. When it asks if it is for personal or work, disconnect your network connection, THEN choose “Set up for an organization” and select Next. You will get an OOBE error. Reconnect your network and choose Skip and you will be prompted for a username and password.
If in step 5 above you selected “Set up for an organization”, you have taken care of a lot of this. You will notice that a large number of apps normally with Windows will be missing (i.e. Bubble Witches, etc). It is amazing how many gigabytes are often devoted to these games most people never play. If for some disturbing reason you want all this, select “For personal use” when prompted.