Ubuntu Remove Mysql.service in Systemctl

After installing MySQL 5.7, I do not want to start MySQL via systemctl.

It's unconvenient and complicated for maintainer. Actually, I like the way

that software should be installed by source package.

Solution to remove service:

systemctl disable mysql.service

cd /lib/systemd/system 

or

cd /etc/systemd/system

rm mysql.service

systemctl daemon-reload