by Emma Richardson.
1. If the users were originally authenticated with LDAP, then you need to change their accounts to whatever authentication you want to use now.
2. You also need to make sure that your other enrolment method is enabled.
3. You need to be sure that the external database (if that is what you want to use) has the exact same user info as the previous LDAP server.
4. If the users are already in Moodle, then make sure that manual authentication is enabled and then change all your users accounts to manual from ldap (auth field).