Things writing into the root user directory make me nervous, as do batch-deleting things. I might be persuaded that moving them into a directory to see if anything breaks would be reasonably safe, but only after a complete backup of both FreeNAS configuration and all volumes to another device. And then only with an extra bootable USB repair stick, hip waders, several rolls of duct tape, three sizes of vice-grips, and, of course, eye protection.