I have switched from using mod PHP in Apache to using PHP-FPM. It was always done via restarting apache in the past, so this was never an issue for me. How do I restart the service now that it is running this way?
This depends on how you have it installed. Depending on the repo that you downloaded PHP-FPM from, you might have a different name for the package. If you installed it, you should have a rough idea of the php command. Normally if you just run "php -v", it will load up the standard php library and this isn't what you want. Since this is completely dependant on your setup, this may also be untrue. If you used the remi safe repo and are using various versions it will be something like the following. You can play around with the "php70" part if it doesn't work for you as this will be the part that might vary depending on the system you are using.
systemctl restart php70-php-fpm