You just need to hire sufficient help to retake possession, e.g. movers, locksmith, etc.Good luck.

You break in or hire a locksmith to drill the locks. 

Explain to tenant you are only sending as a precaution.3) Schedule locksmith for day after scheduled MoveOut.We do NOT recommend doing final walk-thru with tenant present as only leads to them pressuring you not to hold them liable for damages.

You can also screw a lockbox to the wall of each property and change the code as necessary.2) We do not replace locks, we use a locksmith to rekey.

My locksmith has my key chart and I simply have him rekey the cylinders after each turnover.

The owner gave permission to go ahead and have a locksmith come out and change the locks but I am assuming the locksmith will want some form of proof of ownership.

Have the owner either bring a locksmith with him or have locks to change all exterior doors as soon as the guy is out. 

But if you do have that set of keys, you could save yourself a locksmith's fees in case if any emergency came up.  

If you aren't handy or don't want to do it, a plumber and an HVAC guy are your two emergency contacts that you really need, followed by a locksmith, pest control, electrician.

Also, go to a locksmith store and purchase the devices that can be installed on windows to lock them without needing to drill into the frame.