does sending a catalytic converter  to be professionally cleaned, will it fix the below threshold bank code an remove yellow warning light 

Probably not.  There are precious metals inside a petrol cat (generally platinum, rhodium & palladium) and they just wear away over time.  The cat needs to be replaced at that point. 

(Fun fact, motorways are now covered in a thin layer of precious metal - sadly there's no cost efficient way to recover it).

Some places may be able to cut open your cat and fit a brand new core inside it, but it's probably cheaper just to replace the whole thing.