Saving photos to laptop then deleting from icloud

I saw some old answers here that said if the photos are downloaded to phone/computer you can safely delete them in icloud but they will still be on your device. I beg to differ. A few years ago I downloaded a large amount of photos from icloud to my computer and then deleted them from icloud. Well, it deleted those photos on my computer also. I'm still trying to recover from that. How can I download then delete in icloud without losing my photos? If I change the name of the files on computer will that protect them? This is a serious issue for me. Please give me a failsafe solution! Thanks so much.