@Schninemaus, you can deactivate the Skin Helper Widgets script and it will disappear from the Video add-ons section under Videos as well as from widgets pointing to that directory. I’ve tested this on my setup here (using the v18 nightlies) and it works like a charm. In the stable release they shouldn’t be re-activated after each reboot, but deactivating should stick. We’ll look into that 
We have to ship the scripts to make sure that the correct minimum versions are installed for our skin to work under v18.
As those scripts are not provided by the Kodi repo in the newest version atm, we can’t rely on automatic installation via internet.