You may want to rethink that procedure. Circuit breakers are not designed to be frequent switching devices and will often fail when used to that end. There are inexpensive manual ON/OFF boxes which are easy to install.
I believe that leaving it plugged in while in "charging mode", or in "ready to charge" mode (plugged into car), is just fine. What was meant was to not leave it plugged into the outlet if it is not plugged into the car. Also the "thumb" trigger is sort of an off switch. It will stop the current charging session, and turn off the green led on the dash. You can then unplug from the car, then unplug from the wall outlet
Thanks for the inputs!
I only charge my Bolt about once a week so hopefully that's not too hard on the circuit breaker. Using the circuit breaker is kind of convenient for me since it is located right next to the door from my garage to the house.
It's not practical in my situation to unplug the Mustart each time since the 14-50 plug is not very accessible (near the floor behind boxes) in my garage and the plug fits tight in the wall socket. I have left the Mustart on all night many times and haven't had a problem yet despite what the manual suggests, so I guess that's OK so long as the Mustart is still connected to the Bolt.
I'll look into adding a separate switch. My NEMA 14-50 socket is a metal surface mount wall box connected via metal conduit to the circuit breaker. If anyone has a suggestion about what type of switch to use and a surface mount box to install it in that would be appreciated. Would you need a double pole 40A switch to handle both phases (two wires) of the 240V? I wonder why Mustart didn't add an auto-off feature once charging completes?