Short answerBack up your vault and check you have its recovery phrase, set up the new phone and confirm everything opens, then sign out of iCloud and use Erase All Content and Settings on the old iPhone. Don't delete photos one by one with iCloud Photos on, or they disappear from iCloud too.
Checklist
- Back up your vault and confirm the last backup time.
- Find your recovery phrase.
- Set up the new iPhone and restore the vault. Open a few items.
- On the old phone, sign out of your Apple Account (Settings → your name → Sign Out).
- Settings → General → Transfer or Reset iPhone → Erase All Content and Settings.
- Remove the device from your Apple Account's device list.
The mistake to avoid
Don't "clean up" the old phone by deleting photos in Photos while iCloud Photos is on. Those deletions sync and remove the photos from every device. Sign out first, then erase.
Frequently asked questions
Does erasing my iPhone delete iCloud photos?
Erase All Content and Settings removes data from the device only. Deleting photos in Photos while iCloud Photos is on deletes them everywhere.
