Or clear data completely, then open the app "for the first time" and immediately log out.
It'll work, but as you've discovered, google made sure that it isn't the happy path.
Also no search (not even by file name), no albums, some editing functions won't work (even though they're local), and a few more annoyances. but also no more backup prompt...
I closed the app, stopped it and cleared the cache. Then restarted it.
The UI is surprisingly sane now. My first impression is that it is much better than before. Everything is neatly layed out in a series of albums, for each the latest images are shown and I can click on the album name and it displays them all.
So I do see my albums. Those seem to be just directories in /Pictures/ which it seems I can edit with the files app?
Am I missing out on anything this way? I don't need search.
All the usualy edit functions like cropping, adjusting colors etc also seem to still be there.
Also is it possible to undo (in case there's something I don't like?) Is it just a matter of adding the app back to your account?
No idea about Lens, because I never used it. Aren't there webapps or web services for everything these days? I do everything that I do only occasionally via webapps. Barcode parsing for example.