This error will pop up when trying to delete a country that has states attached to it. To resolve the error delete all states that are attached to the country.
  1. Click Administration > countries and states
  2. Click on the hyperlink for the country using the state.
  3. Click on the name of the state
  4. Click the drop down arrow next to a state and click delete
  5. Repeat step 3 until all states are deleted
  6. Go back to the country and states screen
  7. Click the drop down arrow next to the country and click delete