Did you know you can restrict users to use Salesforce Classic, How? Below are the steps: 1) Select the Profile of the User. In my case I m using System Admin Profile. 2) Go to Setup --> In the Quick find box --> Search Profiles 3) Select the System Admin Profile. 4) Search for "Hide Option to Switch to Salesforce Classic" . Refer the Below Screeshot. After Enabling the "Hide Option to Switch to Salesforce Classic" for a particular profile, User cannot see the "Switch to Salesforce Classic" option in user profile. Thank you !!!