Here is another environment variable editor and I'm using this one currently. It basically has all the functions and abilities of Path Editor from CodePlex, and much more. It meets all my requirements including being compatible with Windows 10 (Their website is only updated to Windows 8 but I've been using this with no problems on my Windows 10 system) and it is also gratis. It has added features such as an editable tree view, more information provided on variables, backup and restore support (to registry files), error checking, supports multiple languages, can accept command line parameters to modify environment variables, and more. Basically, if you're looking for software that has quite a few tools built into it, choose this one.
Rapid Environment Editor (RapidEE) is an environment variables editor. It includes an easy to use GUI and replaces the small and inconvenient Windows edit box. RapidEE 8.x supports Windows XP, 2003, Vista, 2008, Windows 7 & Windows 8 (including 64-bit versions). If you still use Windows NT or 2000, then use version 6.1. For Windows 9x or ME use version 2.1.