ClickHouse/programs/server/config.d/access_control.xml

<clickhouse>
    <!-- Sources to read users, roles, access rights, profiles of settings, quotas. -->
    <user_directories replace="replace">
        <users_xml>
            <!-- Path to configuration file with predefined users. -->
            <path>users.xml</path>
        </users_xml>
        <local_directory>
            <!-- Path to folder where users created by SQL commands are stored. -->
            <path>access/</path>
        </local_directory>
    </user_directories>
</clickhouse>