How to Permanently Delete a Facebook Account On Android Device
Here is how:
Turn on your Android device.
Tap the Menu button to go to the apps list.
Open any of your favorite web browser from the given list of apps.
After opening the web browser, open Facebook website on a new tab.
On the opened window, provide your login credentials to sign-in to your Facebook account.
Once logged-in to your Facebook, copy or type https://www.facebook.com/help/delete_account in the address bar of the web browser.
On the displayed page, tap the Delete My Account button under the Delete My Account section.
Once done, on the Permanently Delete Account box, enter your Facebook password in the Password field.
In the Text in the box field, type the captcha code displayed in the image.
Finally, tap OK to permanently delete your Facebook account.