In order to start using the Photos app on my mac, which only has a 500gb HDD, I had to plug in a 1TB external, and use that to house the Photos database file. I had to do this because I had more than 500gb of photos.
Now they are all imported to the photos application, and I have verified they are synced up to the cloud.
Is it safe at this point to delete the photo database file from my external HDD, and then reopen the Photos application and start from scratch using my Mac's HDD with "optimize storage" enabled?
I assume it would just download everything from the cloud in a storage optimized way.