I either haven't searched for the right thing or the web doesn't contain the answer.

I have used the following to mount an image and now I need to know the proper way to reverse the process.

qemu-nbd -c /dev/nbd0 <qcow2 image using lvm>

vgscan --cache    (had to use --cache to get the qemu-nbd volume to be recognized, lvmetad is running)

vgchange -ay

lvdisplay

mount <selected qemu-nbd related 'LV Path' found from lvdisplay above> <mount point>

I have done the following:

umount <mount point>

lvchange -an <all qemu-nbd related 'LV Path's found from lvdisplay above>

vgchange -an <qemu-nbd related volume>

Now what?  How do I get the volume out of the list so I can use 'qemu-nbd -d /dev/nbd0' to dis-associate the image with /dev/nbd0?  vgreduce seems to be for volumes which have multiple underlying devices.  I started to use vgremove but, when it started prompting for confirmation about removing logical volumes, I wasn't sure exactly what it was going to do and responded 'no'.

If there is a web reference explaining this specific situation just point me to it - I'm not opposed to reading.  Thanks for the help.