As an NRI, you need no permissions to buy property in India. You can also rent out the property and repatriate your rental proceeds, subject to payment of taxes.

Please remember that an NRI who is an Indian Citizen can sell his Immovable Property (other than agricultural or plantation property or farmhouse) to another NRI. However, the transaction has to be routed through India only. In other words, the buyer has to invest in India by way of remittance from abroad through normal banking channels or by debit to his account maintained with an authorized dealer.
The Sale proceeds of the property must be credited to your bank accounts maintained with an authorized dealer in India.