If in the lowest gear the chain or derailleur is scratching the surface of the motor hub, you will need to shift your bicycle into first gear. With a phillips head screw driver, rotate the L (low) screw on the derailleur clockwise. The attached image shows which screw is the correct one. You will only need to spin the screw about a full turn clockwise. This will bring the first gear derailleur resting position away from the hub.
If issue is not solved through this method, the derailleur hanger may be bent. To get this fixed you will need to take it into a bicycle shop to have them use a derailleur hanger alignment tool to straighten the unit out so that the derailleur sits straight.