The takeover returns St. Louis to a Civil War-era arrangement of state control. A local official calls the move "a clear gesture of white men wanting to control urban areas."
What stops the city then from just disbanding the police force if they no longer have administrative control? Just tell the state they're not going to pay for others to oppress them.
That would ultimately be administrative. The Only Hope on that front would be for police officers to care enough to be upset. But they by and large don't care beyond the paycheck. Give them money and tell them who's skull to cave in and they are on it.
An admin action, but to think of it as revoking their charter. "We as a city will no longer provide material or operational support to a police force" The state would likely try and coerce more taxes from them to make up for it, but major urban centers inevitably hold some heavy sway just by sheer volume of people.