If someone wants to quit smoking marijuana but has been unsuccessful, is there a safer legal med that could help?

NONE THAT I KNOW: I do not know of a detox medication for marijuana. May need to discuss with your physician and see what is the underlying issue that drives you to smoke and try to treat that. Marijuana has an impact on many areas of the brain and this is why a medication to help is not too easy.

Get evaluated: It would be helpful for you see an addiction medicine physician, many of whom are psychiatrists. It's important to review your history, etc, so that any conditions interfering with recovery can be addressed & treated. Otherwise you will be tempted to self-medicate -- going counter to your goal. Research about the possibility of using Naloxone in people recovering from thc abuse, is ongoing.