You can't. Once done, it's done. The only option you have is to create another identity but that shall create new mess so leave it as it is.
The catalytic converter in an automobile is an expanded section of exhaust pipe occurring upstream of the muffler in which pollutants generated in the engine are converted to normal atmospheric gases. It is an essential element in the emissions control system of modern automobiles.
However, in our beloved country we are gifted with all rotten kind of fuels which is why the filter gets chocked and thus needs to be REPLACED. This presence of a chocked filter causes more consumption and thus a heavier car. They clog up and kill your power and mileage. They can also fall apart inside and rattle like children's teeth in the wintertime. Since it costs Rs. 60000+ and not many of us can either afford OR are bothered to buy one, the genuine one is removed and never compensated. The only affect this shall have is that your car be getting all the impurities present in fuels but then, that is just the very case in all the cars we have been owning in the past too, no? From the local vehicles, I guess it is only Honda Civic that is coming with one. So relax and get it done because in the end, you will be getting more power and better fuel consumption!
How? There should be two converters. In the diagram below, the one towards the inner end of the car is to be removed and NOT the one leading out.
IF both are removed, your car shall sound like a rent-a-car vehicle.
As for the place, you'd better be off asking locals to your area. I live in Islamabad so cannot comment. If I were in your place, I would give half the idea to my mechanic like, 'I heard there is some 'jaali' inside and should be removed. Any idea?' If the guy is smart enough to tell why it is present and the reason to remove it, get it done!