There is a power switch on the controller. You can turn the controller off by sliding the power switch up.
If you are looking for a ‘software’ disable, there is no super convenient way yet. You can use the ‘stop operation’ button, but the stop operation bit is currently now saved in non-volatile memory, so if you restart the controller that bit will be lost. An alternative way is to go through each program and set each program to be disabled. In any case, the ‘stop operation’ bit can be easily saved in non-volatile memory, and I will make sure to include this in future updates.