Termination of Tenancy Letter - Squatters? Detroit - Help

Hi! I am very new to BP and real estate. I am a detroit local... bought a nice duplex last week that is occupied. The former owner had the property for a year, and said that they were probably the homeowner's that were foreclosed on. I already had my property manager go down there and leave a card. I spoke to a seasoned Detroit landlord and he told me to leave a termination of tenancy letter and then they will call me. I also am willing to do cash for keys. My question is: Do I leave a note at the same time as the Termination of Tenancy letter saying... "If you leave house in nice condition then I will give you $_____ ? " or what?