It depends, there are many ac motor principles and variations of principles. E.g.
1. 3-phase squirrel cage and wound rotor induction motors have their direction of rotation changed by changing sequence of phases ABC to ACB which is practically implemented by changing two feeder conductor terminations. Conductor 1 on terminal t1 would go to terminal t2 and conductor 2 from terminal t2 would go to terminal t1 in the motor terminal box or at the same motor feeder upstream, e.g. inside the motor starter.
2. Similarly, higher number of phases motors, e.g. four-phase ABCD must be changed to ADCB.
3. A single-phase motor change of rotation direction is more involved and may or may not be possible, if you do not have right conductor ends available in the terminal box.
4. Single-phase and two-phase motors, just like other motors, must have their shaft torque within their rating to start and run, as designed and without any alterations to their starting arrangements. [sig][/sig]