Securely Wipe your iPhone or Android
Below are instructions to securely wipe your iPhone and Android in the event of selling the device, trading it in, passing it on to a new user, or throwing it away. This process will prevent unauthorized access to data that was on your phone once it is out of your possession.
Preparation
First thing is first: backup your files / device.
It’s important to back-up your files on a normal basis, so that in the event of data corruption, you’ll have a “checkpoint” to restore back to. This provides redundancy and ensures you don’t lose any important data.
Important data may include passwords/credentials, family photos, copies of birth certificates and the like. If you have data like this saved on your device, it would be best to back it up.
You can use iCloud on Apple, or your Google Account on Android.
Click on the links below to be brought to the corresponding section of the guide
iPhone
Backup the device by syncing to iCloud
Ensure you're signed out of your Apple ID if it's a Mac
Open Settings
Tap General
Tap Transfer or Reset
Tap Erase All Content and Settings
Enter your passcode and tap Erase
Android
Confirm encryption
Settings > Privacy > Security (may be different location depending on your personal configurations)
Open Settings
Tap System
Tap Reset options
Tap Erase all data and follow on-screen instructions
After that, consider recycling or donating the device.
Remote Wipe
If you use iOS and have an active iCloud account, you will be able to use the Erase a device option in Find My iPhone on iCloud.com. This comes in handy if your iPhone is stolen or lost while traveling and you want to ensure whoever finds it cannot access the contents of your phone (email, texts, contacts, bank apps, etc).
Note that if you have erased a device that was on iOS 15 or later, you will still be able to user the Find My function or play a sound to attempt to find the iPhone even after the remote wipe.
In the event you find your iPhone after your Remote Wipe, you may be able to restore the information on it from an existing backup.
A remote wipe will only take place once the device goes online. If the device is offline when you push the request, and you happen to find the device, you can cancel the remote wipe request.