Bethesda's games are riddled with bugs and Fallout 76 is no exception. It even brought about bigger problems as it will not let you uninstall the beta files unless you purchase the game. It could be either a malicious practice or a mess up.
Fallout 76 is not looking well in the days leading up to its release, as it's due to come out in just two days, on 14 November 2018. As you may be aware already, the beta was initially reserved for those who pre-ordered the game, but they eventually gained the perk of inviting up to three friends to test the game out.
One would think this is a good thing, but as it turns out Fallout 76 is now holding about 50 GB of those free testers' disks hostage. A Redditor going by the name pip12345 posted a short video showing an unsuccessful attempt to remove the beta client from their PC.
The game refused to be deleted and simply blurted out a message saying "You do not have access to this game", further elaborating that the player should check which Bethesda.net account they are logged in with in order to verify it's an account that actually purchased Fallout 76.
Technically, you could log in with an account that did purchase Fallout 76 and then delete the game, but that would be account sharing, which is not allowed on top of being a huge risk for the account holder.
Either way, there is no reason for such an uninstall function to exist in the first place, and now it simply looks like Bethesda is nagging free testers to purchase the game. Fallout 76 evidently suffers from major issues, but completely messing with the user PC permissions on top of formerly deleting the client on its own is the next level of Bethesda bugs.
It remains to be seen for how long the gamers will tolerate these issues, especially now that the modding community is out of the picture with Fallout 76, so they are not coming to fix a broken mess and make it a game worth playing for months, if not years.
Maybe deleting Windows would eventually solve the uninstall problem. It would be hilarious if Bethesda wouldn't let you do that either, prompting you to buy Fallout 76 before allowing you to remove your operating system.