This is a tough spot to be in becase some city building inspections depts wont give a damn if the unit was roach free when tenant moved in especially if its a multi unit a building inspector could order you to correct the problem. BUT unless there is some kind of local ord baring it you are free to treat the unit you self. What you should do is search for what product you will use and send to the tenant via certified or confirmed mail delivery a letter with instructions , you want them to have all kitchen cabs empty, linen closets empty , medicine cabs empty dressors empty , things can be packed into plastic bag lined boxes then the bags tied once they are filled. If you want a fast kill liquid- sprays are best for huge noticeable diffference. Powders are a bit slower but no matter which product you use it is going to take multiple treatment to kill them since it takes time for eggs to hatch. Tenant has little say in how you treat or who does it but you will need to treat entire structure. If tenant wont cooperate with you use certifed or cinfirmed mail again , keep your reciepts with your copies of the letters, Whether tenant likes it or not it can take multiple treatments to get rid of them , any attempts by tenant to block can be used as reason to take tenant to court. ( in end get them out if they repeatedly block your attempts to address it) use a vac to suck up dead ones and make a point of giving tenant proper written notice before you do re checks an re treat the unit, best time to re check the unit is after its dark out since lights can be turned off it will draw them out, make sure you carefully shake down your own clothes too so you dont bring em home.