What is Cal 2 app?

Third party applications apart from inbuilt apple applications are not be installed , they corrupt Mac system files .

To uninstall an app click on finder and go to applications right click on cal 2 app and move to trash , restart the machine and empty the trash it will delete all created or related files of cal 2 app in system library and user library folders , using app cleaner app that is still third party app and is not be used for searching files related to that app .

Read this -

You can uninstall apps you got from the App Store, from other websites, or from discs. You can’t uninstall apps that are part of macOS, such as Safari and Mail.

• Apps downloaded from the App Store: Click the Launchpad icon in the , position the pointer over an app’s icon, press and hold until all the icons begin to jiggle, then click the app’s Delete button . If you later want the app, you can reinstall it from the App Store.If an icon doesn’t have a Delete button, it can’t be uninstalled in Launchpad.
• Other apps: In the finder side bar, click Applications, then do one of the following:
  • If an app is in a folder, open the app’s folder to check for an Uninstaller. If you see Uninstall App or App Uninstaller, double-click it and follow the onscreen instructions.
  • If an app isn’t in a folder or doesn’t have an Uninstaller, drag the app from the Applications folder to the Trash (located at the end of the Dock), then choose Finder > Empty Trash.If you change your mind before emptying the Trash, select the app in the Trash, then choose File > Put Back.WARNING: When you empty the Trash, the app is permanently removed from your Mac. If you have any files that you created with the app, you may not be able to open them.

Delete it from your Applications folder. Some app have uninstallers but if it would launch, I would not fight it.

I use an uninstaller called AppCleaner.app to pull all associated files by simply dragging and dropping from the Application folder to the Dock icon.

http://freemacsoft.net/