you mean you want the sedative effect, without the cerebral effect? i don't think there currently exist any efficient method to do that - although vaporizing tends to leave behind a greater CBD:THC ratio in the vaped bud.
Use higher temps, or just save your bud for a few months (because the THC is the first cannabinoid that degrade during conservation). When I vape old buds, I get a sedative effect very potent.
