What does "Cleans the place out" in bank robbery context?

In Pulp Fiction (1994), Pumpkin says to Honey Bunny:

Pumpkin: Heard about this one bloke, he walks into a bank with a
portable phone. He gives the phone to a teller. The bloke on the other
end says, "We got this guy’s little girl. If you don’t give him all
your money, we’re gonna kill her." Knucklehead walks into a bank with
a telephone. Not a pistol, not a shotgun, a fuckin’ phone. Cleans the
place out.

What does "Cleans the place out" in bank robbery context?