When switching to another method of authentication, you must first disable Kerberos.
To disable Kerberos:
Edit <install-dir>/mss/server/conf/container.properties and set this property to false:
mss.oauth=false
Edit <install-dir>/mss/server/microservices/auth-service/service.yml and set the enabled property to false.
Restart the server.
Choose another Authentication method in the MSS Administrative Console.