How to Disable Windows Authentication in SQL Server
To stop Windows users from logging in, don't create logins for them in SQL Server.

By default, just because someone has a Windows login doesn't mean they have permissions in SQL Server. You have to use the CREATE LOGIN command to map Windows users to SQL Server permissions.

If you don't do that, they can't log in.

Your organization may also be asking for a list of people and groups who already have logins, and who need to be removed. In SQL Server Management Studio, go into Security, Logins as described in the documentation, and you can review the list of logins from there, and disable (or drop) logins who shouldn't have access.