iCloud & iCloud Photos · iCloud storage space and plans
How do I delete files from iCloud Drive to free up iCloud storage?
Short answer: Delete them from iCloud Drive in Finder and empty the Trash — they're removed from iCloud and all devices. They may stay recoverable on iCloud.com for a while; deleting them there frees the space sooner. Move anything you want to keep first.
Delete the files from iCloud Drive in Finder, then empty the Trash. That removes them from iCloud and every device. Deleted iCloud Drive files can stay recoverable on iCloud.com for a while (under recently deleted files), so the space may take time to come back; deleting them there releases it sooner.
Before deleting, move anything you want to keep to your Mac or an external drive — see moving files from iCloud Drive to an external drive. If you only want space back on your Mac, make files online-only instead; deleting isn't needed.