A. Device part of a business infrastructure:
Just don’t change anything; those policy are there for a reason!

B. Consumer device:
1/ If we’re talking about proprietary hardware/software forcing your network to use a specific DNS, then you need to provide more details because you should be able to change it.

2/ There is also the case for a malware:
A fresh start is preferable.
Disinfect the system while offline, then back up the needed files.
Reinstall the system on a new/old formatted drive.
With the exception of taking your privacy/security seriously this time.

They’re constructed hierarchy not natural (That hints that someone didn’t want to be the fuckup alone & created a destructive system for everyone) otherwise we would be living in a socialist utopia.

I invite everyone to listen to this episode, The history of humanity with Christopher Knight https://www.historicly.net/p/the-history-of-humanity-with-christopher