I posted a reply and it disappeared, try again.
If you look on the KB or Baldor site you will see a version in an enclosure with a reversing switch.
This is a special switch as it has a mechanical momentary stop at centre so you cannot go from fwd to rev with one action, it also has a contact that shorts I1 I2 inhibiting and resetting the drive.
You can switch the drive input power off every time, but then the drive has to go through the power up which can be no problem.
Another way is turn off or reverse the A+ A-, but when doing this method you have to short out the I1 I2 to reset the drive so it goes through accel.
Just dropping the pot to zero is not advised and not necessary, even if you are using unidirectional control, you could leave input power and armature connected and just inhibit the drive, the drive would then return to where the pot is set to instead of cranking it up and down once I1 & I2 are opened.
Some just switch the armature back on and off, this is wrong per the KB manual.
Hope this is clearer.
Al.