Click the word SAFARI beside the Apple icon at the top-left corner of your screen. Afterward, select Preferences. A new window will pop, click Extensions. On the right side of the new window, choose the extension you want to disable by unticking the box beside the extension name. If you don’t want to use it, just uninstall the app by clicking the uninstall button. To double-check, open a new Safari window and check the list of extensions at the left part of the Address Bar.