Yes the catalytic converter cleaners that you pour into your gas tank and mix with your gasoline works to clean the catalytic converter as well as the rest of the exhaust system.
The catalytic converter cleaner works by burning in the combustion process and then cleans the carbon deposits out of the exhaust system and catalytic converter.
If you use catalytic converter cleaner every few fill ups of gasoline the catalytic converter will last longer and your engines fuel mileage will improve and your engine will run properly and better.
However if your catalytic converter is severely clogged then the only thing you can do is replace the catalytic converter with a new one.
If your state doesn't do emission testing then I would just recommend removing the catalytic converter and not replacing it.
I had the catalytic converters removed from my vehicles and they seem to run better and I don't have to worry about clogged or failing catalytic converters.