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SKYLANE
Secure erase of iPhone/iPad: I see some content online regarding the topic. I searched the forum here on this topic and found some really old threads, one of which recommended a program called Data Eraser. I am wondering if just a factory reset is sufficient?
Sign out from all iCloud services and from iMessage on the phone, then do a "Erase All Content and Settings" from the Reset options in the General settings.
Then go to iCloud.com and confirm that the phone is not listed as a managed device in "Find My."
At this point, your phone is ready to be handed away to someone else.
Your data was encrypted on the SSD and the recovery key is gone. Nothing of yours can be pulled from the phone, tho you may be able to recover data from an iTunes or iCloud backup, and there will be some identifiable info on the SIM.