(a) able to disable MCAS?
(b) trained on how and when to disable MCAS?
Major design and training errors are at fault unless both (a) and (b) can be answered 'Yes'.'
Yes, in that you can disable all trim via two switches. Although in previous 737 variants you could over ride it just by moving the control column backwards, this was removed from the MAX as it would negate the purpose of MCAS which is purely to push the nose down if you're approaching the stall. The MAX needs MCAS as due to putting ever larger engines on the 737 it as lost the natural tendency to recover that the original design had.
No, as Boeing didn't include it in the training.