Hi @Tao Lian,
At the moment, the option to connect with the different authentication methods is still present for users if SSO is enabled and there isn't a way to disable it. However, if a user connects via one of the authentication methods and tries to log in with it and SSO is enabled then they will be automatically redirected to the SSO login page. This prevents any user from logging in with a different authentication method outside of SSO if SSO is enabled for the enterprise account.
Our development teams are investigating and looking to implement a way to disable the ability to connect to authentication methods if SSO is enabled but at this time we do not have any timelines to share of when this will be available.