It seems to me that you’re on the right track using LR to remove the folders. Just make sure you’re not also deleting the files on disk, right? How long did you let it sit when it appeared “hung”? If the hard disk is working and the LR process is using CPU it’s probably just preparing for the remove, rather than stopped working entirely.
Hopefully you made a backup of the catalog before you started removing things in case you have to End Task on LR and the catalog becomes corrupted.
Alternatives would be to:
Remove smaller subsets of images than the entire C drive.
Open your last backup catalog before you imported the entire catalog and redo the work since the backup was made. This only works if you have a very recent backup.
Export your catalog of images, minus the ones on the C drive to a new catalog, no need to export previews or digital negatives (the photos), then open that exported catalog.
OK, I rebooted LR6 and my C: drive is now gone. I think LR6 hung after removing all the C: folders. The process took quite a long time.
Thanks! I have managed to remove the volume once I removed all the folders.