To remove completely:

  1. Go to Safari menu.
  2. Click Preferences.
  3. Selct the Extension tab.
  4. Select the extension you want to uninstall.
  5. Click the Uninstall button.
You can also temporarily turn off an extension by disabling it on the Extensions page:
  1. Go to Safari menu.
  2. Click Preferences.
  3. Selct the Extension tab.
  4. To turn off an extension, uncheck the Enabled checkbox next to it. To turn on an extension, simply check the box.