Oh jeez.... let me again recommend separate computers for Windows and Linux!
You might think that removing the Linux drive (with it's self-contained boot partition) would be no big deal and Windows would return straightaway. You might be right, if you have more luck than I do.
That's right, removing the EVO SSD on my Dell left me with the same grub>
prompt. I got into BIOS setup and restored the Windows Boot Manager as the first boot device. Yep, that worked. Then I restored BIOS defaults and I was back at the grub>
prompt again. Hmmmm.
It's clear that more information is actually being stored in UEFI/BIOS settings itself, and not only on the boot partitions of each drive. This is new to me, and I'm not actually sure about the best way to resolve it. I'm not worried about it... I can get Windows back, no problem. But I do want to investigate what the best procedure is for a permanent remedy.
This is a great lesson in caution for anyone wanting to dual-boot or use a dual-drive setup. For those who like to "tinker" (like me)... it can be fun and challenging... and a good learning experience. But for @mike_linux
, who needs his computers for his work, this could go from just a bad dream to a nightmare.