Can I remove synced photos from the cloud?

If you are synchronizing collections from Lightroom Classic then those images are smart previews and they don't count against your cloud storage. The only time your cloud storage is impacted is if you use Lightroom (the desktop version or the cloud version) and import master images directly using that version. If you are importing to Lightroom Classic and creating collections and sharing those collections, there is NO impact on your cloud storage.

Hi Marika,

I'm going to assume that because you are in LR-Classic asking questions you are using LR-Classic forum and not the new Lightroom-CC. The easiest way to tell is if your Lightroom icon has square corners not rounded corners (former-Classic, latter-CC).

I'm also gather that you are syncing your images from various Collections you have in the left-hand column located below your Folders.

The one thing that confuses me is that you state you have removed "every synced collection from your latest 2 or 3 LR catalogs..."

The reason why this confuses me is that (I also have multiple collections) and when I stop one collection and start up another, my synced images stop being synced. I only sync from one of my collections. When I start up a different collection, I make sure that my syncing is set to off so as to not confuse or conflict with my other catalogs. I also have nowhere near that many images in my synced collections so I may only provide limited support for you (but willing to try).

also, while it probably doesn't make a difference, you might want to add your operating system so that we know what you're working with. Also, can you please verify which version of LR you are using (e.g., 7.0.1 release).

Hope this will help you on your way to resolve your issue.