MariaDB [zabbix]> select authentication_type from config ;

 +---------------------+

 | authentication_type |

 +---------------------+

 |                    |

 +---------------------+

  row in set (0.00 sec)

 MariaDB [zabbix]> update config set authentication_type =  ;

 Query OK,  row affected (0.00 sec)

 Rows matched:   Changed:   Warnings: 

 MariaDB [zabbix]> select authentication_type from config ;

 +---------------------+

 | authentication_type |

 +---------------------+

 |                    |

 +---------------------+

  row in set (0.00 sec)

 [root@zabbix-server ~]# systemctl restart zabbix-server