Look up one tier. Take it or anything else off the controlled substances schedules this very moment and it will not be illegal. Great, but until there is a federal law, which has to go through Congress to happen, it’s not a ‘right’ and states can declare it legal or not as they wish. It’s the basic premise of the 10th amendment, if the feds don’t declare something as in or out then it’s fair game for the states.

https://en.m.wikipedia.org/wiki/Tenth_Amendment_to_the_United_States_Constitution