You can do it but you will have to check your agreement with builder if there is a clause for assignment.
Via a assignment agreement you can sell your property- builder will charge a transfer fee. but with this you need not register and sell. which project is your property in call for more - Nine Eight Eight Six Seven Four Seven Four Zero Three
The top priority should be registering your property when you buy a house as it proves your legitimacy to carry out any transaction. Even the Supreme Court had ruled last year that all property sales would be considered invalid unless the sale deed was duly stamped and registered.