General suggestion about flat

My father has booked the flat in e-11 sector, and he has paid all the payments. But the building has a noc issue, and it been 2 years, since 2018. I want to know your suggestions now what to do, sell it or wait for noc. I have talked to the builder he is saying we are only waiting for cda noc, we have already applied for it and when we get noc we will need only 2 months to complete it. A long time has passed and i don't know when will cda give the noc. So please guide me about this matter what to do next.

I think the following questions will determine your actions. How much did your father pay and when did he make the final payment? What price are you expecting if you sell it now? Do you have any estimate on what you will be able to get once the builder has the NOC? Do you need the money right away? Has the builder actually applied for NOC?