The best way to completely wipe to your Android device

The default data wipe tool in the Android may not be enough to permanently eliminate the personal data on your old device.
A study from security software vendor Avast has suggested that the factory reset option built into the Android OS isn't effective in eradicating your personal data from old device. The firm purchased 20 used Android smartphones on the  eBay and was able to recover more 40,000 photos 750 emails and text messages and 250 contacts along with the identities of four of the previous device owners and even a completed loan applications. To make matter worse Avast employee were using readily available data to recovery software to get the jobs done.

While Avast and the other companies like it offer data deletion tool there are other step you can go for the securing your personal data when the performing a factory reset.
Step one Encrypting

I recommend encrypting your device before you're getting ready to the wipe it. The encryptions process will the scramble the data on your device and even if the wipes doesn't fully delete the data a special key will be required to the unscramble it.

To encrypt your device on the stock Android enter settings click on Security and select Encrypt phone. The feature may be locateds under the different option on other devices.

Step two Perform a factory reset

The next thing you'll prefer to do is perform a factory resets. This can be done on stocks Android by the selecting Factory data reset in the Backup and reset option in the setting menu. You should be aware that this will erase all of the data on your phone and that you should backup anything you don't want to lose.

Step three Load dummy data

Following step one and two should be enough for most people but there's an extra step you can go for add another layer by protection when erasing your personal data. Try loading fake photos and contact on your device. Why you ask? We'll address that in the next step.
Step four Perform another factory reset

You should now perform another factory reset thus erasing the dummy content you loaded on to the devices. This will make it even harder for the someone to locate your data because it will be buried below the dummy content.
Still feeling a little paranoid ? Repeat step three and four as many time as you likes. As I mentioned above though for the most people simply following step one and two should be enough. Without the encryptions pin which are the overwritten in the initial factory reset it will be almost impossible to unscramble your data.

Then again you could always the take a hammer to your phone or the toss it in to the toilet. You know if you aren't interested in the selling it.