Can my father withdraw 15000 monthly from his retirement corpus of 8 Lakhs

It is impossible to get the kind of return you father is looking for! If he wishes to get Rs. 15,000 - 20,000 per month from his retirement money of Rs. 8.00 Lakhs, then he is actually looking at a return of 22.5% - 30%! Getting this kind of returns is just impossible to the best of our knowledge.

With average or moderate risk, your father can invest in mutual fund MIPs and withdraw through monthly SWP mode. In that case, he should not withdraw more than 9-10% annually (monthly Rs. 6,000 - 6,500 or so).

You may check the returns of top performing MIPs from here https://www.advisorkhoj.com/mutual-funds... Thanks