# mariadb -p
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 173
Server version: 10.11.11-MariaDB-log MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> stop all slaves;
MariaDB [(none)]> reset all slaves;
MariaDB [(none)]> quit
Bye
# systemctl restart mariadb

個別のスレイブスレッドを完全に消し去る方法

# mariadb -p
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 173
Server version: 10.11.11-MariaDB-log MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> stop slave 'スレッド名';
MariaDB [(none)]> reset slave 'スレッド名';
MariaDB [(none)]> quit
Bye
# systemctl restart mariadb