Do not do this. Terrible advice.
Throttle body / carby cleaner is not designed to be used while the throttle body is on the engine. Throttle body cleaner is an extremely harsh substance which will eat rubber seals and gaskets like they're nothing. Its a great chemical but not for spraying in to your engine.
For this purpose there is something called 'engine conditioner' or 'upper engine cleaner' which is designed specifically for spraying in to inlet manifolds and throttle bodies and is completely safe for seals/gaskets. Its an expanding foam so when you spray it in to your manifold it expands and gets in to every little crevice to remove carbon build up.
Throttle body cleaner will certainly remove carbon build up too, but it will destroy any gaskets or seals it touches in seconds