How to remove mutton smell while cooking?
I am one of those people who really doesn't like the smell of mutton/lamb for at least the first couple of hours if I'm making any type of curry.

Whilst cooking from raw, I'm not sure you can do more than cook in a well-ventilated area.

However, for your final dish, there's a 'cheat' I use, which started as being borrowed from an Indian Restaurant trick known as the 3-pot method. [Oddly, this trick, which I've known for 30 years, seems to have not a single Google hit]

If you really want the smell to be gone, do this the day before...
Cook the mutton separately in a thin 'curry broth' using minimal ingredients, maybe just a little onion &amp; oil to fry your bhoona/bhogar spices in at the start, then add some generic curry powder &amp; simmer gently for a minimum of 45 mins, though I prefer 3 or 4 hours so any fat really renders down.
Strain off the meat &amp; you can then either discard that 'broth', or use it to make further masala gravy/sauce base, &amp; allow the meat to cool separately. Save in a sealed container in the fridge overnight, then the next day add the meat to your actual dish.