How to delete old DotA 2 item builds created before the guide system?

With the patch from 20 February the new guide system is online which provides skill builds and item builds. I have been using the online tool to create those builds, but my old itembuilds saved in \Steam\userdata\XXX\570\remote\itembuilds are still there and cannot be deleted. Moreover when I want to pick one of my custom guides these item builds are still suggested. Is there any way to safely delete those?