npf_ruleset_remkey
int npf_ruleset_remkey(int, const char *, const void *, size_t);
error = npf_ruleset_remkey(rlset, ruleset_name, key, len);
int npf_ruleset_remkey(npf_ruleset_t *, const char *,
error = npf_ruleset_remkey(fd, ruleset_name, key, sizeof(key));