1. Make sure your Android's SD card is in place. If you need to insert the SD card, you may need to remove the back from your Android.

-Tablets and phones use microSD cards, which are miniature versions of the SD cards found in cameras and such.
-In some cases, you'll need to remove the battery from your Android as well before you can access the SD slot.

2. Open your Android's Settings [ Register or Signin to view external links. ] It's a gear-shaped app in your Android's App Drawer.

3. Scroll down and tap Storage. You'll find this option about halfway down the Settings page.

-On a Samsung device, tap Device maintenance.

4. Tap your microSD card's name. It should be below the "Portable storage" heading.

5. Tap . This option is in the top-right corner of the screen.

6. Tap Storage Settings. It's at the bottom of the drop-down menu.

7. Tap Format or Format as internal. If you want to set up your SD card as an internal storage option, tap Format as internal. If you're simply attempting to erase your SD card, tap Format.

-You may first have to tap Storage at the bottom of the page on a Samsung device.

8. Tap ERASE & FORMAT. It's at the bottom of the page. Doing so will begin formatting your SD card for your Android device.

-This process should only take a few seconds. Once it's complete, your SD card has successfully been reformatted.

and you're finished! Hope this is useful for you guys!