456 Oxygen Sensors?

Have you read your OM? I'm not specifically familiar with 456 OM, but there's usually quite a bit of solid technical information (although maybe on the more modern models they've dumbed down the OM and shifted the tech stuff to the WSM).

I'm doubtful that you could remove the O2 sensors and still have good operation. How "smart" is your 456 (OBD-I, OBD-II, something else)? Do you have "Check Engine" warning lights?

 

The answer to your question fills books printed by both Bosch and Ferrari so it is impractical to try to answer here. The system in a 95 456 is rather simple compared to the ones that followed and any problem should be able to be resolved by a quality, well tuned in Ferrari mechanic. If you are having nagging problems I would submit they are with the person working on the car and not the car itself.

As to your comment about the emission system plaguing every 90's Ferrari, that is just not true. For starters with the exception of a few added components, there is no "emission system".
The emission systems on modern cars are are fully integrated into the engine management system and are that systems ability to so accurately manipulate and operate the motor that it achieves the desired goal of cleaner exhaust.

The plaque if there is any is with the inability of people who have not kept up with automotive technology continuing to try to work on them.

And no, you cannot just disconnect the O2 sensors and there is no good reason to if you could.