I customized Google Search - Disable left option sidebar by Kenjiro@userstyles for removing the ugly new Google left sidebar in the case of my country -Uruguay.
In fact, you can do the same for any country.

1. Click Install with Stylish
1. Click 'S' icon at the right bottom corner of Firefox
2. Manage styles
3. Select this style 'Remove Google...'
4. Edit
5. Replace 'www.google.com.uy' with 'www.google.com.xx' -your country
For example www.google.com.ar for Argentine; www.google.com.uk for United Kingdom, etc.
6. Save

If you have any doubt, contact me.