Short version: You don't. Longer version is it requires some very specific and careful editing of the registry which is in no way recommended, and could potentially have some unintended consequences. If you don't use this Rhino3D program any longer, you could simply remove it from your system, and the uninstaller for the program should take care of it.

So, either remove the program or just learn to live with an odd entry. You could just set 7Zip or the Windows zip archive handler to be the default choice for zip archives. Then it doesn't matter if any other programs are listed as potential programs to use, because it will default to using one of the other two programs.