The temperature is OK but the fan motor in the air conditioning unit is still going.. and has been for a while.
How do I turn it off from the thermostat?

Most have a setting for "FAN"... it should be off. Otherwise it will run constantly. It is separate from the Heat or Cool settings.

Are you asking about the fan outside above your compressor or the fan inside your furnace which blows air into the home air ducts?