Hi Suraj. I'm Greg, an installation specialist, 10 years Windows MVP, and Volunteer Moderator here to help you.
See MVP's Shawn Brink and Kapil Arya's tutoriasl here on how to edit System Variables via registry to avoid greyed out settings:
https://www.tenforums.com/tutorials/121855-edit...
https://www.kapilarya.com/change-user-and-syste...
Also the marked Answers here:
https://answers.microsoft.com/en-us/windows/for...
https://superuser.com/questions/1360611/editing...
https://superuser.com/questions/1467734/i-am-ad...
I hope this helps. Feel free to ask back any questions and keep me posted. If you will wait to choose if I resolved your problem, I will keep working with you until it's resolved.
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