How would I create a "website blocker" application.

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C#

VB

website

I want to create a small application in which the user can select out of presets of websites (e.g social media preset, would block Instagram, Twitter, Facebook from being accesssed) or they can enter the URL for a website to block.
The user must be able to unblock the website from the application after they initially block it.

How would I create this / What's the code. (C#, VB.net

Thanks.
Much Appreciated.

What I have tried:

Ive tried coding an application where it successfully blocks one website at a time, but inorder to unblock you must manually clear it by going into System 32 -> Drivers -> etc and editing the "hosts" notepad document. I would like to find an easier way.