There are a number of tools that can display /repair variables in the environment, but thought I would show the real way of getting to and editing the actual paths.
Vulkan along with about 20 other system paths are now created for Win10 1803 , except the OS isn't installing them from initial install, in fact it took a ton of re-work and a roll-back to get windows-10 to finally install and setup correctly. I have tested this on 3 different systems and they all came out about the same ...
Thought I would pass the info along, up until now people saw only fifteen or sixteen paths. Is Vulkan that important apparently so. I don't mess with any of the VM in windows-10 anymore and I still had to run out of my way to get that crapware onto all my box's fyi