How do I delete photos from iCloud and backed up photos?

If you had enabled iCloud Photos then the Photos are not backed up.

iCloud backup doesn’t include information that is synced and stored in iCloud, like Contacts, Calendars, Bookmarks, Mail, Notes, Voice Memos, shared photos, iCloud Photos*, Health data, call history and files you store in iCloud Drive.

*-If you had turned on iCloud Photos & Messages on iCloud, your content is automatically stored in iCloud and is available on all devices that use the same Apple ID

Enabling iCloud for Photos, Notes, Videos, Reminders, Messages, and more, as depicted in the provided picture, means that if you delete any or all data from one device, it will also be removed from iCloud and all other devices linked to the same Apple ID. Likewise, the reverse is true as well.

Where do I find delete on my new 27?

photo and video deleted backup