Windows 10 seeing a bootable installation that doesn't really exist

I've had to reinstall Windows 10 Pro from scratch onto my main storage device (an NVMe drive) a number of times in recent months. One annoyance is that sometimes when booting it gives me a choice of Windows installs to boot from, however, there is only one actual installation (the new installed one). The other installation it sees must be an SSD that used to have a Windows 10 installation, but has had all its visible files removed. How do I fix this SSD so it will no longer be seen as a bootable Windows installation without losing the files/folders that I have put there? What/where is the hidden information (that doesn't show up when I make hidden files visible)?

GregJ7 said:

One annoyance is that sometimes when booting it gives me a choice of Windows installs to boot from, however, there is only one actual installation (the new installed one).

Click the Start button and type msconfig to run the System Configuration utility. On the Boot tab you can select and delete this redundant extra boot option.

How to Delete Boot Loader Entry on Boot Menu at Startup in Windows

Yes, that is what I did to fix the annoyance. But why was it in the boot list in the first place? There is no \Windows\ Folder on the other drive, for example.

GregJ7 said:

Yes, that is what I did to fix the annoyance. But why was it in the boot list in the first place? There is no \Windows\ Folder on the other drive, for example.

This can happen when you do an install with another system already installed. You say you removed 'visible files' but did you remove hidden system files from the old C: drive? And what about the hidden recovery partition (and EFI boot partition if it's a UEFI system)?. Seems you left enough clues behind for Setup to think there was another system still installed, so it set up dual-boot.

@AddRAM, for the new install, yes.

Bree said:

This can happen when you do an install with another system already installed. You say you removed 'visible files' but did you remove hidden system files from the old C: drive? And what about the hidden recovery partition (and EFI boot partition if it's a UEFI system)?. Seems you left enough clues behind for Setup to think there was another system still installed, so it set up dual-boot.

Aha, this is what info I was looking for. I have attached a snapshot from Disk Management. I do not know what is actually kept in "System Image," "EFI System Partition," or even whether the MBR is always on the "SSD 1TB" partition. Can I delete the "EFI System Partition" (and/or "System Image" partition?) without losing the data or access to it on "SSD 1TB?"

I also stumbled on the fact that swapfile.sys, pagefile.sys, and hiberfil.sys are still in its root directory. I happened to be using 7-Zip which showed them. I found no other way to actually see these super-hidden files. Can I delete any of them?
Edit: I now see that attrib from the command line shows pagefile.sys and swapfile.sys, but not hiberfil.sys. Presumably they are invisible because of the "S"ystem attribute and not just the "H"idden attribute. I still don't know how to just use Windows 10 to show me there is a hiberfil.sys there.

Disk 0 still has an EFI System Partition. That's your problem. Delete that partition.

GregJ7 said:

I also stumbled on the fact that swapfile.sys, pagefile.sys, and hiberfil.sys are still in its root directory. I happened to be using 7-Zip which showed them. I found no other way to actually see these super-hidden files. Can I delete any of them?

Edit: I now see that attrib from the command line shows pagefile.sys and swapfile.sys, but not hiberfil.sys. Presumably they are invisible because of the "S"ystem attribute and not just the "H"idden attribute. I still don't know how to just use Windows 10 to show me there is a hiberfil.sys there.

In File Explorer it is easy to tick the box to show hidden items, but to see system files too you need to open Options and un-tick the box for 'Hide protected operating system files (Recommended)' on the View tab.