I don't see any way he has this power... As a note, DC has the 25th highest violent crime rate in the US
https://abcnews.go.com/Politics/trump-hold-news-conference-crime-dc-after-threatening/story?id=124528406
At an extraordinary news conference on Monday, President Donald Trump revealed plans to take over the Washington, D.C. police department and deploy National Guard troops in the nation's capital to combat what he says it rampant violent crime that statistics show is actually decreasing.
"We're here for a very serious purpose. Very serious, very," Trump said. "Something's out of control. But we're going to put it in control very quickly, like we did in the southern border. I'm announcing a historic action to rescue our nation's capital from crime, bloodshed, bedlam and squalor and worse. This is Liberation Day in D.C., and we're going to take our capital back."
He said he was declaring a public safety emergency in order to put the Washington police department under federal control and station the National Guard on the city's streets.
Trump announced that Attorney General Pam Bondi will be taking command of the Metropolitan Police Department and DEA Administrator Terry Cole will be interim federal commissioner of the force.
He delivered his message standing beside Bondi, Secretary of Defense Pete Hegseth, U. S. Attorney for the District of Columbia Jeanine Pirro, FBI Director Kash Patel and Interior Secretary Doug Burgum who will all play a role in the takeover Trump announced.