Uninstalling an app will depend on where it was installed from. If the app was downloaded from the App Store, select the Launchpad Icon from the Dock, then position the mouse over the app that you want to remove, and hold in the mouse. A X will appear above the app - click on this X to remove the app. If the app was not installed from the app store, open Finder, then select Applications. Here you can either drag an app to the trash or click on the uninstaller if the app provides it.