Procedure for an NRI to sell a property?

please see

Q1.: Can such property be sold without the permission of Reserve Bank?
Ans.: Yes. Reserve Bank has granted general permission for sale of such property. However, where the property is purchased by another foreign citizen of Indian origin, funds towards the purchase consideration should either be remitted to India or paid out of balances in NRE/FCNR accounts.

Q2.: Can sale proceeds of such property if and when sold be remitted out of India?
Ans.: In respect of residential properties purchased on or after 26th May, 1993, Reserve Bank considers applications for repatriation of sale proceeds up to the consideration amount remitted in foreign exchange for the acquisition of the property for two such properties. The balance amount of sale proceeds if any or sale proceeds in respect of properties purchased prior to 26th May, 1993, will have to be credited to the ordinary non-resident rupee account of the owner of the property.

Q3.: Are any conditions required to be fulfilled if repatriation of sale proceeds is desired?
Ans.: Applications for repatriation of sale proceeds are considered provided the sale takes place after three years from the date of final purchase deed or from the date of payment of final installment of consideration amount, whichever is later.

it is simple.  How to you purchase and built a house in india.  Follow the same method to sell.

Part of the question is that what are the things required from a USA citizen to sell his property

The procedure to sell might require PAN number, which I didn't need at the time of buying since there was no such thing in 1992. How do I pay tax?

sir, what do you ask?  you are already admited that you are an NRI. How to you purchase the property in India.  Please follow the same method to sell.  Thats all