Thanks for the answer. I keep forgetting to subscribe to the threads I post so this is why this reply is late.
I have read the linked documentation and there seems to be no way to determine the file location? So I conclude there is no way to extricate the photos from Office Lens? (Which basically makes the app useless.)
I also checked the OneNote application on my PC (whatever this programme does) but the file I had created on OneNote on the phone, which includes nothing but all the photos I have taken with Office Lens, does not get synced.
When a picture is taken, it typically is immediately tossed into the Camera Roll folder under Pictures in OneDrive, that is, if you have auto-upload enabled. Its bound to be in your phone's camera roll, upload it manually if you must.
OneNote is a syncing note taking app. I suspect the OneNote app on your PC isn't connected to your MS account, and thus won't sync. What version of OneNote are we talking about here on your PC?
you generally want to delete or push to OneNote (if you use it) the scans (there's a limit of 10 at once.)
Since they all showed up in OneNote at once, I suspect you never saved them to OneNote or deleted them. Deleting from Office Lens does not delete from your phones camera roll.