A tell tale patch of droppings hint at the presence of unwanted visitors
Occasionally a small black shape skitters across the floor
Then they could be exterminated one of two ways: brute force, or extermination chemicals (e.g. laying down poison or a bug bomb or something).
Brute force would involve needing some sort of blunt implement and pretty good reflexes. Your character just swats at whatever infestation has manifested until they kill them. This would probably be an agility test.
You hold your frying pan aloft and wait until the creature comes into view
With a deft motion, you bring your frying pan down on the vermin and....SPLAT! Got it!
Chemical extermination would reliably get rid of the infestation fairly quickly, perhaps opening up a business opportunity for an extermination firm.
If you wanted to be extra sneaky, perhaps you could even add live traps that allow you to capture the vermin to deploy elsewhere >:)