shutting it down could actually cause more trouble because by default you have quick start enabled in windows which will cause some information to be kept in the memory, as a result, it is not really a "restart"
There should be a launcher in the game's directory, open that and navigate into settings there are lots of settings there, vsync is probably around there, just disable it. Don't try to find the option in the in-game options cuz it's not there.
Yeah try editing the ini file but don't forget to make the ini file read only by right click > properties. If the vsync on is the default option, the game might change back that option you manually edited back to the default which is vsync on. Good luck