Summary:Your selling or otherwise planning on getting rid of your existing Android smartphone or tablet, but you want to make sure that all your data has been securely deleted. Here's what you need to do. By Adrian Kingsley-Hughes for Hardware 2.0 | February 7, 2015 -- 10:20 GMT (02:20 PST) Your selling or otherwise planning on getting rid of your existing Android smartphone or tablet, but you want to make sure that all your data has been securely deleted. Here's what you need to do. Backup all your data, because once it's gone, it's gone. Next, plug the charger into the device so it's getting power for the deletion process. This is important because the process can take hours. Go to Settings > Security > Encrypt phone (or Encrypt tablet) to begin the process on Android 4.4 or lower, or go Settings > Security > Screen lock to begin the process on Android 5.0 and higher. You will be guided through the process. Set a strong password. Don't bother encrypting the SD card because you can pop this out rather than wiping it. This process can take over an hour, so be patient and make sure you have the time. Go to Settings > Backup & reset > Factory data reset and then tap Reset phone. Once this process is complete your data is gone. Technically, it's still written there on the flash memory in what is now reported as free space, and will eventually be overwritten. Because it's encrypted it recovering it would be difficult. However, if you want to completely eradicate it, jump to the next step. The best way to get rid of the encrypted data is to overwrite it with new data. There are two ways you can do this. You can load some big files onto the device until the storage is full up and then delete these files, or you can use a custom app such as iShredder to digitally "shred" the data. That's it! Your data is now gone, and you're safe to pass the smartphone or tablet on.