Enabling and Disabling Lightning Experience for Users and Profiles
To disable lightning experience for the specific users:
1. Create a custom profile.
2. In the profile, navigate to the Administrative Permissions category.
3. Uncheck the checkbox against Lightning Experience User.
4. Click Save.
5. Assign users to the new custom profile
All the users under this profile in the org cannot view the pages in lightning experience.
Enabling lightning experience for the users:
1. Create a new permission set
2. Go to System >System Permissions > Edit.
3. Edit properties in the new permission set.
4. Enable to checkbox against Lightning Experience User.
5. Click Save.
6. Add users to this permission set using the Manage Assignments option on the permission set.
For information about how to set up user access to lightning experience, see
Salesforce Documentation.