Unable to remove Windows recovery disk from Startup Manager

Hi all. I hope someone can help me with this. When I boot my MacBook into the Startup Manager (holding Option on boot up) I see a disk choice labeled "Windows" that I seem to be unable to remove, and if I select it for startup, it goes into what looks like a Windows recovery screen. These are the steps that seem to have gotten me here:

1. I had macOS installed plus a Boot Camp Windows 10 installation that both worked just fine.
2. I installed Parallels 14, and it gave me the choice to use the Boot Camp installation as my Windows VM so I did so. That seemed to work just fine, too. I have a feeling it tweaked the Boot Camp installation in some way, but I don't know now.
3. I decided to quit using the Boot Camp installation as my Windows VM, so I installed a brand new Windows VM in Parallels in macOS.
4. When I decided I was happier with the new Parallels VM than with the Boot Camp VM, I deleted it from the Parallels Control Center, and then I tried to use the Boot Camp Assistant to remove the Boot Camp partion. Boot Camp Assistant told me it was unable to delete the partition. I wish I had made a note of the error message, but unfortunately I didn't.
5. So I decided to just delete the Boot Camp partition using the Disk Utility. That seemed to work except...

Now if boot my MacBook into the Startup Manager, I see both a macOS and a Windows disk. Choosing the macOS disk boots macOS no problem. Booting the Windows disk gets me into a Windows recovery screen.

I can see no trace of the Windows partition anywhere else, not in Disk Utility and not in the System Preferences Startup Disk window. If I run "diskutil list" in a terminal window, I get an output that is identical to another MacBook I have that has never had Boot Camp or Parallels on it:

/dev/disk0 (internal):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                         1.0 TB     disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         1.0 TB     disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +1.0 TB     disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            626.2 GB   disk1s1
   2:                APFS Volume Preboot                 44.5 MB    disk1s2
   3:                APFS Volume Recovery                517.0 MB   disk1s3
   4:                APFS Volume VM                      1.1 GB     disk1s4

I even tried an NVRAM reset, but that didn't make any difference either.

In all honesty, this issue does not affect the usability of my MacBook at all, but I would feel better if I could get rid of that Windows recovery disk in the Startup Manager. Any ideas how to fix this, short of a complete reinstall of the MacBook?

Details: MacBook Pro (15-inch, 2016, with Touch Bar), macOS 10.14.3 (18D109) Mojave

Thanks for any help!