How to wipe an Android phone data before selling it online?
Do so by going to Settings> Backup & Reset> Factory Data Rese.
More safer method is to use professional data eraser tool, which will erase all personal and system data with no chance to recover.
If you’re planning to trade in your old Android phone for a discount on your new phone, sell it on a trustworthy website like Recell Cellular, Gazelle, or Swappa. But, before selling first you have to wipe all your data by resetting it to factory conditions. Make sure you have a copy of all your data such as pictures, videos, documents, call logs and texts. Before selling your phone online, you have to wipe all your data, and remove your accounts from the phone. Follow the instruction carefully:
Go to the Settings section of your android phone
Choose System > Additional Setting> Reset options
After that, you will be presented with three choices depending upon the Android version. The first option “Reset Wi-Fi, mobile & Bluetooth” is sometimes useful if you’re having trouble with connectivity. The second option “Reset app preferences” will restore all your apps and notification defaults. Neither of these will delete the data on your android phone. That’s the role of the third choice, “Erase all data” and that’s the one you have to select.
You’ll get a warning screen reminding you that your data will be erased, along with all the accounts you’re currently signed into. Select “Reset phone.”
If you have a password or some other security setup like pin or pattern, you’ll be asked to enter it.
After that, you’ll get another pop-up screen asking if you’re sure this is what you want to do. Are you sure? Then hit the “Erase everything” button.
That’s it! The entire process usually takes not more than three minutes. Your phone will reboot and begin with the usual opening questions, such as language, network, account, etc. Once you see those, you’ll know that it worked perfectly.
Hi DanielCooper0987. I highly suggest checking the guide Important Steps to Take Before You Sell Your Phone. Hope that helps!