You can toggle the Side menu from Templates Settings. Please follow the below steps to hide the side menus in the worksheets.

  1. Goto Settings
  2. Goto Navigation Options
  3. Select the Navigation Type as Index(Home)
  4. And Apply the settings

Please see the below screen-shot for pictorial representation of the above settings:

 

Now , you can see the index page to navigate sheets. And Back to Mainsheet /Index sheet in all worksheets.