If an Admin has configured WebCenter to use only LDAP, and the LDAP config is wrong, it is not possible to login to WebCenter to change the configuration. Here is how to login using Basic Password authentication even if it is disabled in WebCenter.
Login to the WebCenter WebServer computer, this can be a remote login, but you MUST be logged into the WebServer computer.
Open a browser of your choice.
In the URL window type localhost:8081/WebCenter_Inst.
The login page will come up, you must login as the user admin.