How to prevent logins using Windows Authentication in SQL Server? SQL Server supports creating logins using SQL, Windows, certificates and asymmetric keys. Is it possible to remove the option of creating logins with Windows authentication (and just allow SQL authentication for example)?
Natively you cannot prevent using Windows Authentication in SQL Server.


  SQL Server supports two authentication modes, Windows authentication
  mode and mixed mode.
  
  Windows authentication is the default, and is often referred to as
  integrated security because this SQL Server security model is tightly
  integrated with Windows. Specific Windows user and group accounts are
  trusted to log in to SQL Server. Windows users who have already been
  authenticated do not have to present additional credentials.
  
  Mixed mode supports authentication both by Windows and by SQL Server.
  User name and password pairs are maintained within SQL Server.


Microsoft also recommends using windows authentication over SQL Server logins.


  We recommend using Windows authentication wherever possible. Windows
  authentication uses a series of encrypted messages to authenticate
  users in SQL Server. When SQL Server logins are used, SQL Server login
  names and encrypted passwords are passed across the network, which
  makes them less secure.


As commented by Nick you can programmatically restrict the creation of logins from Windows user account, trusted domain account, or Windows groups.

Reference: Authentication in SQL Server

A similar question was also answered here by Paul White.