They didn't need to disable MCAS - they needed to disable the stabilizer trim motors - which is done with the two switches. The stabilizer trim is set via wheels that are right alongside the pilots, wheels that are marked in black and white stripes to make any motion readily visible. Wheels the pilots can manually overpower to overcome the motors by brute force if required.
These pilots seem not to have known about one of the major control surfaces:
Rudder, Elevator, Stabilizer, Ailerons, Flaps, Spoilers. That's it. Six things to know about.
This suggests that Lion Air has really poor training for its pilots. Of course, they are the same people who put the plane back in the air without finding out what went wrong when the exact same thing happened to the trim on at least three previous flights or leaving a sticky-note on the control panel to warn that the stab trim motors should be shut off.