There are, however, a few ways to make sure your data is actually erased forever.
Because what you know already when you do a “factory reset” and consent to erase everything on your Android device that all of your files would be cleaned out for good. But you’d be wrong.
Several researchers have discovered, data can be retrieved with the right tools despite a factory reset has been carried out. That’s due to the fact when you delete some thing, the data file on its own isn’t basically over-written — the mobile just throws away all the info on the file, basically tossing it in with no matter what free space you have. Recoverable data can be a real privacy problem if you ever prepare on selling or donate your Android phone.
Encrypting your Mobile
Encrypting your Android device is the most powerful method to avoid its data from being restored. By encrypting your device, you are basically trying all the information and securing it away with a unique key. When encrypted, the data can’t be decrypted without entering a password.
In case your device is running Android 5.0 Lollipop or lower (and supports encryption), it’s strongly suggested you turn on encryption (Settings > Security > Encrypt phone) to scramble its data prior to doing a factory reset.
Basically, using this method, you’ll be eliminating scrambled data which is virtually unrecoverable.
Overwrite it
Now that you’ve encrypted your phone, factory reset it and removed everything, move on to next step and ensure that the new destroyed encrypted data is a lot more jarbled and useless by overwriting with new junk data.
Proceed and setup your device again, but now don’t sign into any Google accounts or anything. As soon as your device is setup as new, proceed and start recording a video for as long as you can, within the highest resolution. Repeat around it is advisable to fill up all the space.
Then repeat factory reset again. But in case you want to make it simple, only one encrypt-and-reset will do the trick for almost all.
