Here are general steps on how you can install, turn on and uninstall extensions for Safari on MacOS.
Installing Extensions for Safari
1) Open Safari on your macOS.
2) Open the Safari menu on the top bar, then click on Safari Extensions…
3) The App Store will open and take you right to the Extensions section. From here you can select the extensions you want to add from the selection.
4) With the extension that you want, click on the Get button. It will then give you a button to Install. When selected, it will prompt you with your Apple ID sign in. Sign into your Apple ID.
5) Once signed in, the download will start automatically. Once the download is finished, go to the Safari menu on the top bar and go to Preferences…
6) Once opened, go to the Extensions tab. You will see the extensions that are installed listed on the left. They will be unchecked by default. To enable them, click on the check box next to each extension you want to use.
7) Close out of Safari and then reopen it, the extension icons will show up on Safari to the left of the web address bar.
1) Go to the Safari menu on the top bar, open Preferences…
2) On the Preferences menu, go to the Extensions tab. Select the extension you want to uninstall. You will see an Uninstall button for that extension.
3) You will receive a message that the extension is part of an application. With this, click on the Show in Finder option to bring up the Finder right in Application.
4) Hold the Control key and click on the extension you want to delete and select the Move to Trash option.
Note: Safari will have to be fully closed (no dot below the Safari icon on the Dock). If you receive a message saying that it can’t be moved to the Trash because some of its extensions are in use, then you will need to close out of Safari completely.
5) You will be prompted to enter your password. Enter your password to uninstall the extension from Safari.
6) If you decide you want to reinstall the extension. Repeat the steps in section one. The only difference is that instead of clicking on the Get or Install buttons on the Safari Extensions Page on the App Store window, you will have a Cloud download icon to click to immediately download the extension.