Stephen writes: I’m trying to install an update to an application on my Mac, but the installer won’t work if the old version of the app, or associated processes, are running. How can I quit or stop an app in OS X so that I can either delete it or install an update on top of it?
It’s true that, in general, you need to close or quit an application before you can install an update to it, modify its files, or remove it from your Mac. Many applications do this for you when you launch an update installer or uninstaller program, but if you’re stuck with an open process or app, here’s how to get rid of it.
First, make sure that the application itself is closed. Using Command + Tab, cycle through your open applications and quit the app you’re trying to update or remove along with any apps that might be associated with it. If your app is a system utility that doesn’t have a front-end window, check for other ways to access the app’s settings, such as the menu bar.
For example, the file syncing and sharing app Dropbox uses a menu bar icon to provide access to the app’s settings as quit functions. Simply click the menu bar icon, then the settings gear, and choose “Quit Dropbox.” Look for similar options in other apps.
Next, if the app is automatically launched at startup, you can configure your Mac to not launch the app and then reboot to clear it away. To prevent an app from auto-launching, go to System Preferences > Users & Groups. Select your user account from the list on the left and choose “Login Items” on the right. Find your app in this list, select it, and press the minus button at the bottom of the list to prevent the app from automatically launching at boot.
Now, just reboot your Mac and the application should not be running after the system logs you back in to your user account. From here, you’ll be able to delete the app, change its associated files, or perform an update.
Finally, you can use Activity Monitor to kill pesky apps or processes that just won’t close. Launch Activity Monitor from ~/Applications/Utilities and make sure the drop-down menu at the top of the window says “All Processes.” Next, use either the search box or browse the list alphabetically to find the process(es) associated with your app. Select each one and press “Quit Process.”
Activity Monitor will ask you if you’d like to “Quit” or “Force Quit.” Always try “Quit” first and, if that doesn’t work — if the app is frozen, for example — repeat the process and try “Force Quit.”
To ensure system stability and minimize the chance of problems, perform the steps above in the order listed (quit using the app or menu bar, remove app from auto-launch, force quit from Activity Monitor) until you find one that works.
Absent more complicated issues, such as locked or corrupted files, once the app and its processes are no longer running, you can delete it from your Mac or safely perform updates.