How can I erase all information on this phone to resell

Hello this is what you must do!

1- settings

2- account

3- Backup

4- restore values

and Done.

I strongly advise you to encrypt your phone's data before resetting it to factory settings. Deleting all the files does not actually delete them all, anyone with a spare hour or two can extract deleted information from the phone.

By encrypting your phone you make sure that even if he/she got the deleted data, the data would be useless.

To encrypt:

1. Go to "settings"

2. "General" (skip if old settings layout)

3. "Security encrypt device"

4. Make sure it is connected to a charging outlet

To reset

1. Go to "settings"

2. "General" (skip for old settings layout)

3. "Backup and Reset"

4. Uncheck "Automatic Restore"

5. "Factory data reset"

6. "Reset Device"

Done

P.S It is advised you encrypt your phone twice or more, but if you are an impatient person, you may encrypt it once, which should be enough. Not all Pre-Owned phone buyers are looking to extract data from your phone.

How does a factory reset work?

When you do a factory reset on your Android smartphone, it’s supposed to wipe it clean, but it doesn’t. It deletes the addresses of all of your data, so it no longer knows where it’s stored, but it doesn’t actually overwrite the data. That being the case, it’s possible for someone to employ off-the-shelf recovery software and get some of that data back. Let’s look at how to wipe your Android smartphone properly.

The first step is to encrypt your data. This option is built in to Android, and requires you to enter a PIN or password every time you turn your phone on. It means that anyone attempting to recover data from your phone after you will need a special key to decrypt it, and they won’t have the key.

Fully charge your phone or keep it plugged in to the charger while this process is running, because it can take several hours depending on how much data you have.

The exact method for navigating this next step will differ slightly from phone to phone. It will generally be Settings > Security > Encrypt phone. But on a Samsung Galaxy, for example, you want to go to Settings > Lock screen & security > Protect encrypted data. You have the option to encrypt the SD card as well, but if you’re passing the phone on, we would recommend removing it instead.

If your phone came with Android 6.0 Marshmallow or above, it will be encrypted by default, and you can skip to the next section. If you’re unsure about which version of Android your phone is running, then take a look in Settings > About device/phone > Software info. Keep in mind that it will only be encrypted by default if Android 6.0 Marshmallow was installed out of the box.

To delete/erase everything in your device you can see the following tutorials here:

ErasePhone

ios data eraser

Here is a video about how to permanently and completely erase all the data on Samsung phone.

Hope it will help.