How to wipe Android phone?

From the settings menu, it's called Factory reset.

Yeh, Factory Reset from the settings. However does an S6 have FRP(Factory Reset Protection)? If it does, make sure you clear and de-register your Google Account from it, otherwise whoever buys the phone will be howling loudly, and demanding your Google Account login details.

The S6 was released with Android 5, so will have factory reset protection.

One thing to be aware of is that Factory reset is properly called 'Factory Data Reset' It removes all your installed apps, and data including photos, videos and audio files. but won't necessarily remove call logs, SMS/MMS logs and phonebook. I've not tested this on anything newer than Android 6.0 but it holds true up to at least that version.

Call logs, messages, contacts are wiped by a reset in my experience. In my rooting days I did an awful lot of resets, sometimes several in a week, that was all with Android 2, 4 and 5, and never once saw any of that stuff survive. Are you certain those weren't being resynched when you signed in again?

No, what I did was a factory reset, and did not log on with my Gmail, I then installed AFLogicalOSE.apk (From the Santoku forensics Linux distro) and it found all the call and message related data. It did survive the Factory Data Reset, but would not have been visible to the average user. I discovered this aver a year ago while researching for a piece I was writ ing about digital forensics.
I wonder if this might be something peculiar to the phone I was using (HomTomHT17 with nearly stock android 6). I believe that HomTom is a sub brand for Doogee, so maybe not the most representative example.

Interesting. I'll try to remember to try that with one of my old devices if I can find time. Very strange though, since those databases should just be stored in /data/data like all other app data (I mean I know the actual addresses of some of them from memory), so odd that they should survive a wipe of that partition.

Shouldn't matter for anything more recent since the storage is encrypted by default these days and the reset should wipe the encryption key. But that does remind me that for old devices we used to recommend people who really wanted to be safe to encrypt the storage before doing a reset, to render data unrecoverable (or at least unrecoverable without a prohibitive amount of effort).

There are only two sources of media in your S6 that you need to worry about, the internal storage chip itself and your SIM card (a lot of Android phones have microSD card slots so normally it would be three, but Samsung opted to not include one in the S6 models). So don't forget to remove your SIM card (that typically retains just your cellular account info), and then be sure to go into your Settings menu and remove your Google account from this phone (that removes the initial Google account authentication you would have added in when you first got your phone). Now, just to be sure, check the Storage menu in the Settings menu and confirm that the internal storage is encrypted. It probably is but Android didn't start encrypting the internal storage by default until Lollipop, and even then it wasn't universally done until Marshmallow:
https://www.theverge.com/2015/3/3/8143607/android-lollipop-default-disk-encryption-performance
When the internal storage itself is encrypted, all the data stored on it is protected from external, prying eyes. If on the remote chance the internal storage in your S6 isn't encrypted, enable that now yourself. Now with your Google account removed, when you do a Factory Reset that removes any traces of your previous ownership. If someone does try to do something like recover old data, because the storage media is encrypted the data itself just appears as random data bits. (The media does play this up as a possibility but statistically it's not very likely here in the real world, as most people when buying old phones are not going to be forensically poking through the storage media trying to recover the previous owner's data. It's not a simple a task as portrayed in the movies.)

As I know, you can use Android data eraser tool to help you erase all personal data from your old Samsung galaxy s6 device. The data being erased in this way can not be recovered by any data recovery software. So there is no need worrying about personal information leaked.

If you want completely erase everything then you have to shutdown your phone and follow the below steps.

1. Press and hold Power button with Home + Volume UP buttons simultaneously.
2. When the Samsung logo appears, release the “Power” button, but continue to hold “Home and Volume UP" button
3. When the Android logo appears on screen appears, release all buttons.
4. Use the Volume button to toggle the selection to “wipe data/factory reset“, then press “Power” to choose that selection.
5. Use the “Volume Down” button to select “Yes — delete all user data“, then press “Power” to choose.
6. After erase everyting it will ask to “Reboot system now“. Press “Power” to choose that selection.

It is possible to break the encryption, but I do know from when I was at Uni (in 2012) when we had a forensics officer from the police, who told us about a case when they needed to access an encrypted partition on a hard disk - they sent it to the Home Office, whose cyber forensics team spent around four months to break the encryption and reveal the (very nasty and illegal) contents. So don't worry about the average hacker - it takes a well resourced government department to break decently strong encryption - even then it takes quite a while.

There's no shortage of verbage being posted here but really, just delete your Google account, remove your SIM card, and do a Factory Reset. Once done, your previous ownership will be removed from the phone.

All the hype that every used phone is going to be forensically examined and its data will be restored is based solely on if you are actually being targeted by someone or some organization (with all the necessary skills, and a lot of time and resources). Otherwise, when you dump off your phone into the resale market or whatever, it's just going to get recycled or disposed of as e-waste, or someone is just going to reuse it as their own phone, not unlike how you using it for.

If you do want to believe that there's some secret society that does actually extract data from every phone, just take a hammer and smash your phone into pieces. (... and before someone trolls that Google is already doing this, it's not a matter where this is happening covertly. Google's Terms of Service, that we all have to agree to, states in plain wording what it's doing.)

@svim said "All the hype that every used phone is going to be forensically examined and its data will be restored is based solely on if you are actually being targeted by someone or some organization (with all the necessary skills, and a lot of time and resources)".
Just so, As I said earlier, it's just not practical or feasible for anyone short of a government agency to realistically extract meaningful data from a properly wiped phone; even that takes a considerable amount of time.

Always be wary of information from someone who is trying to sell you something. And always remember that old, out of date information persists forever on the Internet.

So how old is that article? What you say about data recovery was true in 2011: back then phone storage was unencrypted and the phone used USB Mass Storage for file transfers with a computer. This meant you could plug it into a computer and use regular file recovery software. These days they use MTP, which doesn't give the level of filesystem access that recovery software needs, and the storage is encrypted so you need to both recover the data then crack the encryption.

If you want to make sure that GCHQ or the NSA couldn't retrieve the data then sure, you will need to take special measures (personally I'd recommend taking a chisel to the storage chips). But for Joe Regular Criminal, forget it - they really aren't going to be able to do this.

As the S6 is old it's possible the the storage is not encrypted (though it will use MTP). But there will be an option to encrypt it. So why not do that and then remove your account from the phone and then reset it. That should suffice for any plausible attempt at data recovery.

Doris Barney said:

thanks.. but i heard that factory reset can't erase data completey and it can be easily recovered by some data recovery, right ?

see this:
https://www.safewiper.com/tutorials/how-to-delete-text-messages-android-phone.html

I was worried!

Click to expand...

A simple solution is to just try and do a recovery yourself then. If your phone's internal storage is already encrypted do a Factory Reset and see what happens for yourself when you use one of those utilities to restore your data. If it isn't go into the Settings menu and encrypt the storage, and then see what happens when you try to restore your data.
Or if you don't want to see what the actual results will be, again, just take a hammer to your phone for your own peace of mind.