At some point in your Android phone or tablet’s lifetime, you’re probably going to need to perform a factory reset on the device. Whether you’re giving the device to a friend, trading it in to get a better device, or sending it off for a warranty repair, it’s handy to know how to completely wipe all of your personal information off of the device (and optionally, the SD card). In this guide, we’re going to go over how to do that complete wipe so you never have to worry about leaving personal info on a device when you no longer have it.

The first step in this process is backing up your data if there’s anything important on it that you don’t want to lose. Whether that’s your Angry Birds data or your family photos, you want to make sure you’ve got a copy of it somewhere. We’ve covered backing up your apps and data as well as your photos, so feel free to check out those guides to make sure you’re not losing anything. And if you don’t backup your contacts to your Google account, we even have you covered on that end, too.

It’s worth mentioning that with many of the methods in those guides, your data is backed up to your SD card. If you’re planning on wiping the SD card and migrating the data to a new or replacement device, you should back up the data to your PC so it doesn’t get lost when you’re wiping everything.

Everything completely backed up? Good. Your second step is going to be to find where your factory reset is in your phone or tablet’s settings. On stock Android, it will be listed near the Accounts group in your settings menu, which you can see below. (The screenshot shows Cyanogenmod, but if you’re running any similar ROM, the Backup & Reset option should still be in a similar place) 

On a skinned version of Android like TouchWiz, you may have to do a little more looking. Samsung’s Galaxy S 4 lists their reset option under the accounts tab in settings, below all of the accounts that are signed in on your device, but the Note 2 and Galaxy S III should list it in a place more similar to stock Android. Other manufacturers may move it around slightly too, but as a general rule, it’s going to be near where your accounts are listed.

The next screen is going to be pretty basic. You’ll want to tap the last option that reads “Factory data reset.” 

Selecting that option will show you the accounts signed in to your device, and a confirmation button for erasing the phone or tablet. Select that option and your device will reboot and wipe itself.

There is no going back from that point, so if you haven’t backed everything up, you should go do that before going any further.

After it runs through a reboot and wipe, the phone will boot back up just like it came out of the box. No apps, no data, no accounts on it. If you were just wanting to reset the device to freshen it up and start from a clean slate, you can stop at this step. All of the files stored on your phone’s internal memory and SD card (like those backups you made, any pictures or songs, etc.) will still be there. If you want to wipe all of that, too, keep reading.

There are two ways to manage this next step; you can either wipe your device from your phone, or connect your device to your PC and wipe everything from there. If you want to do it all from your device, you’re going to need some type of file manager, (most phones come preloaded with one, but there are many available in the Play Store) and if you’re doing it from your PC, you’ll just need your USB cable.

We’re going to use Astro File Manager to manage this from the phone. Astro is a very robust, powerful file manager that can handle a ton of different operations, plus it’s free. After getting it installed and running, you should see either one or two SD cards on the main screen. SDcard0 is normally the device’s internal storage, while SDcard1 is the actual SD card, if you have one in your device.

Select whichever memory you want to wipe first, and you’ll be able to see everything stored on the device. You essentially want to delete everything here, but there’s a catch; making sure you don’t miss any hidden files. Tap the menu button on your phone to pull up Astro’s View Settings, and make sure to check the “Show Hidden Files” option. This will show all the folders on that storage device that are normally hidden from view.

Once those are showing up (you’ll know because hidden folders have a period at the start of their name, like .Android) tap the multi-select button at the top of Astro, which will then cause an action bar to appear at the bottom of your interface. Tap the more option on the right side, followed by “Select All,” and then Delete. It should take Astro a minute or two to completely delete all of those folders and files from your internal memory. Follow the same steps for SDcard1 if you have or want to wipe the SD card in addition to your phone’s internal memory. 

Now, if you would rather do this from a computer, you’ve got more options. You can either connect your phone to a computer to wipe everything, or put your SD card into a card reader on your computer. If you’re wiping the internal memory, it’s generally better to connect the device directly to the computer, since it can handle erasing both the SD card and internal memory. (We’re going to be using Windows 7 for this example. If you’re running OS X, any Linux distro, or Chrome OS, your experience may be a little different here)

Once connected, your device will show up like a removable flash drive. With an AT&T Galaxy S 4, the device shows up under My Computer as a Portable Device SGH-I337. Obviously that model number will change depending on your device, but that can give you an idea of what you’re looking for. You might be prompted to install additional drivers. If so, install them so your computer can read the data on your phone. 

Opening it up like a USB drive shows an Internal Storage folder, as well as an SD Card folder if you have one. From here, you’re going to want to do basically the same thing we did with Astro earlier; open up each folder, select all the folders and files in it, and delete them. To make Windows show you hidden files and folders, open the Start menu, type “hidden files” and select the Control Panel option “Show hidden files and folders.” That will open up a window with view options for folders. Around the sixth item on that list will be a radio button that will change whether your computer shows or hides those hidden files. You’re going to want to select the option that lets those show up, then click OK at the bottom.

Last step here; open whichever folder you want to erase (Internal Storage or SD Card) to see all of the folders and files. Now you’re going to want to select all of the folders here, which is easily by pressing Ctrl + A. Now right click them and select Delete, or hit the Delete key on your keyboard. Poof, all gone. 

Rinse and repeat for both your SD card and internal memory as necessary, and you’ll soon have a device that’s running just like it did out-of-the-box. You can sell, trade, or loan the phone without worrying about your personal info leaking to whoever ends up with your phone next.