My AC is already tilted few degrees to let water drain out of indoor unit properly but still smell there.
So yesterday i washed indoor coils again with sprayer but that didn't help much although smell was reduced. (the reason for using sprayer was to not let water enter pcb and short it because its indoor pcb is not splash resistant)
So as a final resort today i have poured 9 - 10 liters of dettol water in indoor to kill germs growing inside indoor drain.
For now smell issue is completely resolved. Let's see when it appears back.