In case a particular process takes long time to respond, consume lot of memory and CPU power that slow down your Mac or even be hand, you will need to stop that process immediately to free up the memory and release your Mac.
In Mac OS, you can kill/stop a running process/program by using either Activity Monitor or Force Quit in the Apple Menu that I mention below:
1. Kill Program/Process With Activity Monitor
Open Activity Monitor (can be found in Applications => Utilities), click on a program/process you would like to stop/kill then click Quite Process icon on the top and confirm you action.
Mac Kill Running Process With Activity Monitor
2. Kill Program/Process With Force Quit Application
If you want to stop a particular application (Firefox, Safari, etc) that is running, Force Quit Application should be easier as Activity Monitor will list all processes that are running and need more steps.
1. Click on Apple icon and click on Force Quit … menu:
Mac Apple Icon Force Quit
2. Select the application you want to kill then click on Force Quit button and confirm your action.
Mac Force Quit Application
