How to keep the photos on my Mac while removing them from iCloud?

I have photos on my MacBook Air that have synced to iCloud. I forgot to switch off sync in the Photos App. I do not need photos to be synced to iCloud as I have them saved elsewhere. Now my iCloud storage is full. I have switched off iCloud in the Photos app setting but the photos are still there on iCloud. When I try to manually delete the photos, it says they will be deleted from iCloud on all my devices. I just want to keep the photos on my mac and remove them from iCloud. Is there any way of doing this? Thanks in advnace for your help.

[Re-Titled by Moderator]