No - membership of the EU was by Treaty.
However if say Welsh politicians instructed the population to stop paying their taxes to HMRC but to a Welsh equivalent, declared that Wales refused to accept the authority of Parliament and instructed councils not to pass business rate income, road tax...
That is a very slanted view of the real situation!
Most of the individuals charged with abuse of power, misappropriation of funds, sedition etc. have been released on bail. The few that have been remanded in custody have been either charged with the most serious of offences, are a flight risk...