I installed a custom raster function in ArcGIS Desktop (version 10.2 I think) a couple of years ago. It has persisted in my installation of ArcGIS through several version upgrades. How do I remove it?
did you install them from github?
From the link, Creating custom raster functions—Help | ArcGIS for Desktop
they aren't clear where the persistence might come from, but I suspect there is something stored in your user profile, so you might want to use windows explorer and check there to see if ther is something within or without the Arc* stuff that may be causing the problem