My step father has recieved a letter by hand saying he needs to vacate his rented business premises in 30 days?

The gates will be bolted and the sheriff will not allow access any longer. I would suggest that he get what he wants out of there asap. In some places the sheriff will actually place the renters personal property on the curb. The notice he received is the eviction process. If he doesn't leave, the sheriff may phyically remove him and his personal property, and anything that is attached to the walls, etc will remain the property of the landlord.