Remove a memory/SD card from an iPhone?Take these mobile phone precautions before you hand off your phone to a total stranger:
1. Backup: The first step to keep in mind is to take a partial or entire backup of your mobile phone. If you want to keep files such as music, photos, or documents—basically anything that’s stored on the phone, you need to transfer them on a secure device.
2. Remove the SIM card and memory card: Once you’ve backed everything up, the next step is to remove the SIM card and any internal storage such as an SD card.
3. Perform a factory reset: Once you’re confident that you have everything backed up and saved, it’s time to wipe your mobile by performing a factory reset.
After performing these activities, you can easily sell your phone online without any issue. Based on my opinion, these are the best websites to sell your phone:
• Recell Cellular
• Sell Cell
Thanks for your suggestions.Remove a memory/SD card from an iPhone?
Let's get iPhone specific :
Be sure you have signed out of Find My iPhone before doing that factory reset.
If you backup your device to iCloud, then you don't "need to transfer them on a secure device."