Android - Remove Most Frequently Used Apps Container from Apps menu

To remove the most used app bar follow the steps :

1. Open Google Now ;
2. Open the sidebar (hamburger menu or slide from the left) ;
3. Click the "Settings" button ;
4. Scroll down to the Home screen section
5. Toggle the option "App Suggestions".

Source : Reddit.

There was recently an update (Android 7.1.2) that makes the previous answer incorrect, the new directions are as follows:

1. Press and hold on the home screen until this dialogue appears:
   2. Then simply press the settings icon and change the one that says app suggestions.

Source: experimenting