There are two ways to explicitly shut down ICM:
1) To exit ICM from the Main Window using standard Apple functionality:
Click the ICM Main Window's Close Button (upper left hand corner of the ICM Main Window):
A confirmation pop-up menu opens:
Choose Yes or No as applies to what you want to do.
2) To exit ICM using the Apple Menu:
Select File, then Quit.
A confirmation pop-up menu opens:
Choose Yes or No as applies to what you want to do.