For PC, press Ctrl+Alt+Delete to access the Task Manager. From the Task Manager you can force individual programs to quit
For Mac, they must open the Activity Monitor in the Utilities folder of their Applications. From the Activity Monitor you can force individual programs to quit
If the problem persists, you may be required to remove programs from the computer completely:
On a PC, open Control Panel > Programs > Uninstall > and select/remove the program from the list.
On a Mac, locate the program in the Applications folder and drag to the trash.