TLDR: you follow the appropriate checklist for your aircraft.
How do you disable plane AI
There is no Artifical Intelligence (AI) in passenger transport aircraft.
Colloquially, the term "artificial intelligence" is used to describe machines that mimic "cognitive" functions that humans associate with other human minds, such as "learning" and "problem solving"
So far as I know, avionics systems pretty much have to follow a rigorously tested and designed but fairly traditional style of imperative and deterministic programming that does not involve the kinds of techniques that computer scientists might associate with AI, such as knowledge-based-systems, rule-based systems, fuzzy-logic, inference engines, etc.
737 MAX crash was caused by the AOA indicators giving faulty info to the AI which crashed the plane
There have been two crashes in which MCAS (not AI) is thought to have played a part. After the first crash, but before the second, the FAA issued an Airworthiness Directive (AD) that specified what action to take in the case of "uncommanded nose-down inputs".
Required by AD 2018-23-51
In the event of an uncommanded horizontal stabilizer trim movement,
combined with any of the following potential effects or indications
resulting from an erroneous Angle of Attack (AOA) input, the flight crew
must comply with the Runaway Stabilizer procedure in the Operating
Procedures chapter of this manual:
- Continuous or intermittent stick shaker on the affected side only.
- Minimum speed bar (red and black) on the affected side only.
- Increasing nose down control forces.
- IAS DISAGREE alert.
- ALT DISAGREE alert.
- AOA DISAGREE alert (if the option is installed).
- FEEL DIFF PRESS light.
- Autopilot may disengage.
- Inability to engage autopilot.
Required by AD 2018-23-51
Disengage autopilot and control airplane pitch attitude with control column
and main electric trim as required. If relaxing the column causes the trim to
move, set stabilizer trim switches to CUTOUT. If runaway continues, hold
the stabilizer trim wheel against rotation and trim the airplane manually.
It may be that the pilots in the second incident did not follow the revised checklist for this situation, or were not able to for some reason. More recent information suggests that following the runaway stabilizer
checklist can disable MCAS but also disables the ability to adjust trim "manually" using the thumbswitches on the control column. At some point there was a change
in the wiring/operation of the two STAB TRIM CUTOUT switches so that both have the same effect rather than being able to selectively disable automatic trim while
retaining the operation of the thumbswitches. This only leaves manual operation of the trim wheels - which can require a lot of strength in some circumstances.
The faulty AoA sensor and the actions of MCAS may have contributed to the accidents but there are other causative factors that need to be understood by anyone dealing with this situation. Battle over blame, BBC
Note that Boeing will now fit AoA disagreement indicators to 737s. I believe they also have issued MCAS revisions.
how do you completely disable the flight computer
There isn't one computer.
There are many computers. Usually there are different computers for each function and there are multiple redundant computers for the same function. If you want to disable a computer, you need to know what function you want to disable and know what effect that will have on everything else you are relying on. This is why there are checklists for pilots to follow for non-routine and for emergency situations.
I'd like to see an answer telling how to disable all of them
Modern passenger transport aircraft are very complex, there are many breakers, in multiple locations. Some of those locations are sometimes not in the cockpit.
It isn't possible to give, in this Q&A website, a complete list of all breaker locations for all passenger transport aircraft currently in service.
It caused accidents when it happened in test flights but Id like to take a risk.
People who like to take risks do not (or should not) pilot passenger transport aircraft like the 737.