You might not know that instead of using web-browser, we can terminate your FaceBook ID forever using iPhone or iPad in seconds.
Terminate Permanently Facebook ID in iOS – map:
Access Settings through Facebook app >Help Center >Editing your Account > Deactivating & Deleting Your Account > How do I permanently delete my account > Confirm.
Finally, Enter your password to confirm that you are 100% sure to terminate your FaceBook ID forever.
There is another way to do on any web-browser such as Safari, Google chrome,…. without using iPhone or iPad that you might want to take a look on: How to terminate Facebook account permanently – Delete forever.