Just completely wipe your phone as if it were new. You can do this easily with a simple google search!

Once you’ve wiped your phone ensure you only sell it on reputable websites and only AFTER you have been paid. I’ve sold about 4 iPhones on EBay and have had no issues with buyers trying to con me but still be wary.

You might get messages from scammers asking you to sell your phone OUTSIDE of eBay, I.e you won’t have eBay protection then. So be careful.