You can only disable password authentication if you set up your account to use single sign-on credentials. Otherwise, password authentication is required and cannot be modified.
Sign in to your DigiCert account.
In the left menu, select Accounts > Sign-in settings for all-account-access users.
On the Account details page, in the Sign-in settings for all-account-access users section, the Password only pencil (edit icon).
On the Manage password only page, select Disable password authentication.
Select Save.