They should hire an exterminator to look into it.

The best you would be able to get is a Letter of Environmental Protection, which tells everyone you did illegal work then hired a licensed deleader in to fix it.

That said, hiring anyone is a risk. 

I hire an attorney every time I close anything now.

I currently own/manage 10 units and have a contractor that I use for all of my property, the issue is he works full time and although he's a fantastic contractor there's only so many hours in a day and sometimes thing...

How are you handling on-site tasks, have you hired someone to stop by once a week or so?

Air seal it well as you put it back together, then do a blower door test and hire an HVAC guy that will aggressively size an inverter heat pump.

That area pictured is a great place to start looking for lower-maintenance SFH rentals that are around the 1% rule (avoiding the more expensive pockets like Castle Hills or Shavano Park).

Hiring yourself means working with a complete rookie.

On the other hand, when practicing property management, you hire a manager to oversee all of your day-to-day activities.