You could try removing Elixir and installing with Scoop (https://scoop.sh/). It takes care of paths for you, and installs exes in your home dir, which eliminates any possible file permissions issues. It also makes updates easier in future.
If you don’t solve your problem, perhaps include a bit more info eg. are you using powershell or cmd? And list your current env vars (env in cmd, or dir env: in powershell)
