On WRM 9.7.5 and later, a boolean application setting in the core web.config will prevent any LDAP server connections from being made by the WRM backend.
To disable LDAP, change the DisableLDAP setting in the core web.config to True.
Once completed, exceptions will be raised in the core log if any attempt is made by the WRM core to connect to an LDAP host (e.g. clicking Connect in the Administration LDAP Configuration screen).
Disable Windows LDAP Sync Service
If LDAP is disabled in the WRM core, the associated LDAP Sync Service must be stopped and either disabled or uninstalled to prevent it from making any LDAP host connections. This service must be disabled on the server where WRM is installed.