Why not have the utilities disconnected and have the post office temporaraly stop delivering mail to the address and remove the numbers from the mail box.
The utility companies mey hesitate to cut off service to an occupied residence, especially if the squatter was paying.
Signing a document to re-direct somebody else’s mail might not be legal.
Also, I wouldn’t be surprised if the average mail carrier wouldn’t even realize the numbers missing from a single box for weeks if ever.