tskill
You can use the tskill command to close all instances of a program such as Excel. Simply press the Windows Key and R to open Run. Then enter the command followed by the name of the program you want to shut down.
tskill explorer will close Windows Explorer
tskill chrome will close the Google Chrome browser
tskill excel will close Microsoft Excel
In Task Manager refer to process image name in order determine the name of the software you want to close.