How to Enable Disable Startup Services in Ubuntu

Enable / Disable startup service

Apache2

# Disable a startup service
sudo systemctl disable apache2
# Or
sudo update-rc.d apache2 disable

# Enable a startup service
sudo systemctl enable apache2
# Or
sudo update-rc.d apache2 enable

MySQL

# Disable a startup service
sudo systemctl disable mysql

# Enable a startup service
sudo systemctl enable mysql

Remove / Add

# Delete
sudo update-rc.d apache2 remove
#Or
sudo update-rc.d -f apache2 remove

# To add it back
sudo update-rc.d apache2 defaults