How do I disable MySQL on Linux from starting on boot or statup?
MariaDB use systemd as does MySQL. To disable MySQL or MariaDB, from starting on bootup, run

systemctl list-unit-files '*mariadb*' '*mysql*'


If you see mysql.service, try disabling that one first.

sudo systemctl disable mysql


Now you can start and stop MySQL with

sudo systemctl stop mysql.service
sudo systemctl start mysql.service